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Sample records for chromium steels

  1. Chromium-manganese steels of transition class

    International Nuclear Information System (INIS)

    Possibilities of nickel replacing by manganese and preparing the same level of mechanical properties as in chromium-nickel steels due to γ-α transformations taking place during property tests, are studied. Chromium-manganese steels with the composition of 0.05-0.1%C, 13-14%Cr, 5.0-6.5%Mn, 0.2-0.5%Si, 0.03-0.13%N, 0.05-0.01%Al and additionally alloyed 0.3-2.0%Cu, 0.05-0.6%V, 0.3-1.0%Mo, 0.02-0.05%Ca in various combinations have been melted. It is shown, that using alloying and heat treatment one can control the phase composition, austenite resistance to martensite transformation during loading and mechanical properties of chromium-manganese steels of the transition class. The use of the phase transformation in the process of testing determines the level of mechanical properties. The optimum development of the transformation accompanied by a sufficient development of processes of hardening and microstresses relaxation permits to obtain a high level of mechanical properties: σsub(B)=1500 MPa, σsub(0.2)-1130MPa, delta=15%, psi=37%, asub(H)=1000 kJ/msup(2) which exceeds the level for chromium-nickel steels. Steels have a lower cost and do not require any complecated heat treatment regime

  2. Stainless chromium-nickel steels. Chapter I

    International Nuclear Information System (INIS)

    The chemical composition is tabulated of 90 chromium-nickel stainless steels and alloys given in volume %. The values are also given of the corrosion resistance of the steels and alloys. The tables show data on the surface condition or the methods of material working, types and chemical composition of the medium where corrosion resistance tests were carried out, temperature, pressure, time of tests, corrosion rates, corrosion types, and literature references. A total of 35 references is given. (J.B.)

  3. Bainitic chromium-tungsten steels with 3 pct chromium

    International Nuclear Information System (INIS)

    Previous work on 3Cr-1.5MoV (nominally Fe-3Cr-2.5Mo-0.25V-0.1C), 2.25Cr-2W (Fe-2.25Cr-2W-0.1C), and 2.25Cr-2WV (Fe-2.25Cr-2W-0.25V-0.1C) steels indicated that the impact toughness of these steels depended on the microstructure of the bainite formed during continuous cooling from the austenization temperature. Microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of nonclassical microstructures were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2.25Cr-2W and 2.25Cr-2WV steel compositions to increase their hardenability. Charpy testing indicated that the new 3Cr-W and 3Cr-WV steels had improved impact toughness, as demonstrated by lower ductile-brittle transition temperatures and higher upper-shelf energies. This improvement occurred with less tempering than was necessary to achieve similar toughness for the 2.25Cr steels and for high-chromium (9 to 12 pct Cr) Cr-W and Cr-Mo steels

  4. Low-chromium reduced-activation chromium-tungsten steels

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-10-01

    Bainitic microstructures formed during continuous cooling can differ from classical upper and lower bainite formed during isothermal transformation. Two types of non-classical bainite were observed depending on the cooling rate: carbide-free acicular bainite at rapid cooling rates and granular bainite at slower cooling rates. The Charpy impact toughness of the acicular ferrite was found to be considerably better than for the granular bainite. It was postulated that alloying to improve the hardenability of the steel would promote the formation of acicular bainite, just as increasing the cooling rate does. To test this, chromium and tungsten were added to the 2 1/4Cr-2W and 2 1/4Cr-2WV steel compositions to increase their hardenability, and the microstructures and mechanical properties were examined.

  5. Chromium-Makes stainless steel stainless

    Science.gov (United States)

    Kropschot, S.J.; Doebrich, Jeff

    2010-01-01

    Chromium, a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point, is a silvery white, hard, and bright metal plating on steel and other material. Commonly known as chrome, it is one of the most important and indispensable industrial metals because of its hardness and resistance to corrosion. But it is used for more than the production of stainless steel and nonferrous alloys; it is also used to create pigments and chemicals used to process leather.

  6. Stainless Steel Leaches Nickel and Chromium into Foods During Cooking

    OpenAIRE

    Kamerud, Kristin L.; Hobbie, Kevin A.; Anderson, Kim A.

    2013-01-01

    Toxicological studies show that oral doses of nickel and chromium can cause cutaneous adverse reactions such as dermatitis. Additional dietary sources, such as leaching from stainless steel cookware during food preparation, are not well characterized. This study examined stainless steel grades, cooking time, repetitive cooking cycles, and multiple types of tomato sauces for their effects on nickel and chromium leaching. Trials included three types of stainless steels and a stainless steel sau...

  7. Chromium in aqueous nitrate plutonium process streams: Corrosion of 316 stainless steel and chromium speciation

    International Nuclear Information System (INIS)

    This study was undertaken to determine if chromium(+6) could exist in plutonium process solutions under normal operating conditions. Four individual reactions were studied: the rate of dissolution of stainless steel, which is the principal source of chromium in process solutions; the rate of oxidation of chromium(+3) to chromium(+6) by nitric acid; and the reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel and with oxalic acid. The stainless steel corrosion rate was found to increase with increasing nitric acid concentration, increasing hydrofluoric acid concentration, and increasing temperature. Oxidation of chromium(+3) to chromium(+6) was negligible at room temperature and only became significant in hot concentrated nitric acid. The rate of reduction of chromium(+6) back to chromium(+3) by reaction with stainless steel or oxalic acid was found to be much greater than the rate of the reverse oxidation reaction. Based on these findings and taking into account normal operating conditions, it was determined that although there would be considerable chromium in plutonium process streams it would rarely be found in the (+6) oxidation state and would not exist in the (+6) state in the final process waste solutions

  8. Low-chromium reduced-activation ferritic steels for fusion

    Energy Technology Data Exchange (ETDEWEB)

    Klueh, R.L.; Alexander, D.J.; Kenik, E.A. [Oak Ridge National Laboratory, TN (United States)

    1996-04-01

    Development of reduced-activation ferritic steels has concentrated on high-chromium (8-10 wt% Cr) steels. However, there are advantages for a low-chromium steel, and initial ORNL studies on reduced-activation steels were on compositions with 2.25 to 12% Cr. Those studies showed an Fe-2.25Cr-2W-0.25V-0.1C (2 1/4Cr-2WV) steel to have the highest strenglth of the steels studied. Although this steel had the best strength, Charpy impact properties were inferior to those of an Fe-9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa) and an Fe-2.25Cr-2W-0.1C (2 1/4Cr-2W) steel. Therefore, further development of the low-chromium Cr-W steels was required. These results indicate that it is possible to develop low-chromium reduced-activation ferritic steels that have tensile and impact properties as good or better than those of high-chromium (7-9% Cr) steels. Further improvement of properties should be possible by optimizing the composition.

  9. Increase of chromium utilization in stainless steel melting

    International Nuclear Information System (INIS)

    The processes of deoxidizing when melting stainless 18-10 steels in electric are furnaces by the method of remelting with wastes are investigated. The dependences of amount of reduced chromium on silicon consumption are made more precise. It is shown that it is useful to apply aluminium for deoxidation of acid high-chromium slags. Based on the data on pilot melts the extent to which aluminium can be used as a reducing agent for chromium is estimated. 3 refs., 2 figs

  10. Composition and structure of plasma sprayed chromium steel powders

    Czech Academy of Sciences Publication Activity Database

    Schneeweiss, O.; Voleník, Karel; Kolman, Blahoslav Jan

    Praha, 2005, s. 105-111. ISBN 1899072 18 7. [EURO Powder Metallurgy Congress & Exhibition. Prague (CZ), 02.10.2005-05.10.2005] Institutional research plan: CEZ:AV0Z20430508 Keywords : chromium steel * plasma spraying * chromium depletion * Mössbauer spectroscopy Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

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

    International Nuclear Information System (INIS)

    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

  12. Chromium depletion from stainless steels during vacuum annealing

    International Nuclear Information System (INIS)

    The behaviour of chromium during selective evaporation by high temperature vacuum annealing has been investigated by means of energy dispersive X-ray analysis and by neutron activation analysis. It was established that the rate of chromium loss from austenitic stainless steels 316 and 321 is controlled by chromium inter-diffusion rather than tracer diffusion in the alloy. Two important parameters in selective removal of chromium from alloy steels are the variation in the chromium surface concentration with time and the depletion profile in the alloy. The present work gives support for the model in which loss of chromium is dependent on its diffusivity in the alloy and on an interface transfer coefficient. The results showed that the surface concentration of chromium decreased with increasing vacuum annealing time. The chromium depletion profile in the metal was in accord with the previous derived model, apart from an anomalous near surface region. Here the higher resolution of a neutron activation technique indicated a region within approximately 2 microns of the surface where the chromium concentration decreased more steeply than expected. (author)

  13. The diffusion of chromium in a duplex alloy steel

    International Nuclear Information System (INIS)

    Diffusion of chromium in a duplex stainless steel containing approximately 8% ferrite has been investigated in the temperature range 600 to 10000C using the standard serial sectioning technique. The resulting concentration profiles exhibited up to four distinct regions. The two main regions are attributed to volume diffusion in the austenite and ferrite phases, the other zones being due to short circuiting paths. Volume diffusion in the austenite phase is in good agreement with chromium diffusion in Type 316 steel. The chromium diffusion coefficient in the ferrite phase of approximate composition 25 wt % Cr, 5 wt % Ni is given by: Dsub(α) = (6.0(+11,-3)) x 10-6 exp - ((212+-5)/RT) m2s-1 the activation energy being expressed in kJ.mol-1. Little evidence was found for enhanced chromium diffusion along austenite/ferrite interface boundaries. (author)

  14. Chromium reduction from slag on electromelting of stainless steel

    International Nuclear Information System (INIS)

    Specific features of chromium reduction from the slag on electromelting of stainless steel type Kh18N10T according to one- or two-slag procedure were studied. It was shown that one-slag melting technology allows double decrease of chromium losses in the form of incompletely reduced oxides. This occurs due to additional chemical reactions between metal and slag on their combined pouring into the ladle. 1 ref.; 3 figs

  15. Influence of nitrogen on the structure and properties of chromium, chromium-molybdenum and chromium-manganese steels

    International Nuclear Information System (INIS)

    Phase transformations, precipitation processes and properties of the chromium, chromium-molybdenum and chromium-manganese steels with a high content of nitrogen as the dependence on thermal treatment were investigated. In case of Fe-0.08C-18Cr-18Mn-N and Fe-0.08C-18Cr-18Mn-2Mo-N steels the samples in the state after solution at temperature 1050oC and 1150oC and 1250oC and after subsequent annealing in 600oC and 800oC were investigated. heat treatment of the Fe-0.5C-10Cr-N and Fe-0.5C-10Cr-1Mo-N steels included austenitizment from 1000oC with air cooling and hardening from 1000oC with oil cooling and tempering in 650oC and 750oC in two hours with cooling in the air. These investigations show that the influence of nitrogen as an alloy element on the phase transformations, precipitation processes, mechanical and corrosion properties is connected with the presence of molybdenum and chromium in the steel. Nitrogen with these elements creates complex ions with the coordinate number 6. This statement is formed on the base of both calculations and investigation results. (author)

  16. Developing of chromium cast steel on sleeves of heavy machines

    Directory of Open Access Journals (Sweden)

    J. Kilarski

    2010-10-01

    Full Text Available The results of investigations of hardness, impact resistance, abrasive and corrosive wear of selected chromium cast steel with destination on sleeves of heavy machines were introduced in the article. First results of exploational investigations talked over on the end.

  17. New alloys to conserve critical elements. [replacing chromium in steels

    Science.gov (United States)

    Stephens, J. R.

    1978-01-01

    Previous studies and surveys on availability of domestic reserves have shown that chromium is a most critical element within the U.S. metal industry. More precisely, the bulk of chromium is consumed in the production of stainless steels, specifically Type 304 stainless steel (304SS) which contains 18% Cr. The present paper deals with means of reducing chromium in commercial stainless steels by substituting more abundant or less expensive elements with the intent of maintaining the properties of 304SS. The discussion focuses on some of the oxidation and corrosion properties of new substitute stainless steels with only 12% Cr, which represents a potential saving of 33% of the chromium consumed in the production of 304SS. The alloying elements substituted for Cr in 304SS are selected according to their potential for protective oxide formation during high-temperature oxidation; these are Al, Si, Ti, Y, and misch metal which is 99.7% rare-earth metals containing 50 to 55% cerium. Other alloying elements to impart corrosion resistance are Mn, Mo, and V.

  18. Chromium(III) and chromium(VI) surface treated galvanized steel for outdoor constructions: environmental aspects.

    Science.gov (United States)

    Lindström, David; Hedberg, Yolanda; Odnevall Wallinder, Inger

    2010-06-01

    The long-term degradation of chromium(III) (Zn-Cr(III)) and chromium(VI)-based (Zn-Cr(VI)) surface treatments on galvanized steel and their capacities to hinder the release of zinc induced by atmospheric corrosion at nonsheltered urban and marine exposure conditions for 2 years are investigated. Compared to bare zinc sheet, both surface treatments revealed high corrosion protection abilities and capacities to hinder the release of zinc, still evident after 2 years of exposure. The zinc barrier properties of the thinner Zn-Cr(VI) (10 nm) treatment were during the first 100 days of urban exposure slightly improved compared with Zn-Cr(III) (35 nm). However, their long-term protection capacities were inverse. Released concentrations of total chromium correspond to annual release rates less than 0.000032 (Zn-Cr(III)) and 0.00014 g Cr m(-2) yr(-1) (Zn-Cr(VI)) after 1 year of urban exposure. Aging by indoor storage of the surface treatments prior to outdoor exposure reduced the released Cr concentrations from the surface treatments. No Cr(VI) was released from the aged surfaces but from the freshly exposed Zn-Cr(VI). Marine exposure conditions resulted in a faster reduction of chromate to chromium(III)oxide compared with urban conditions, and a significantly lower amount of both chromium(III) and chromium(VI) released from Zn-Cr(VI) at the marine site compared with the urban site. PMID:20462267

  19. Heat resistance of carbon steel with chromium-based gas-thermal sprayed coatings

    International Nuclear Information System (INIS)

    Heat resistance of steel with chromium-base plasma sprayed coating is studied in comparison with chromium coating and base material. The specimens were oxidized at the air under 1250 K during 48 h. Investigations into steel-chromium coating interface were carried out and the structure of cinder was studied. Refs. 7, figs. 2

  20. Intragranular Chromium Nitride Precipitates in Duplex and Superduplex Stainless Steel

    OpenAIRE

    Iversen, Torunn Hjulstad

    2012-01-01

    Intragranular chromium nitrides is a phenomenon with detrimental effects on material properties in superduplex stainless steels which have not received much attention. Precipitation of nitrides occurs when the ferritic phase becomes supersaturated with nitrogen and there is insufficient time during cooling for diffusion of nitrogen into austenite. Heat treatment was carried out at between 1060◦C and 1160◦C to study the materials susceptibility to nitride precipitation with...

  1. Fretting damage of high carbon chromium bearing steel

    OpenAIRE

    Kuno, Masato

    1988-01-01

    This thesis consists of four sections, the fretting wear properties of high carbon chromium bearing steel; the effect of debris during fretting wear; an introduction of a new fretting wear test apparatus used in this study; and the effects of fretting damage parameters on rolling bearings. The tests were operated under unlubricated conditions. Using a crossed cylinder contact arrangement, the tests were carried out with the normal load of 3N, slip amplitude of 50µm, and frequency of 30Hz ...

  2. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    OpenAIRE

    Arh, B.; F. Tehovnik

    2011-01-01

    The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming sla...

  3. Semisolid Slurry Preparation of Die Steel with High Chromium Content

    Institute of Scientific and Technical Information of China (English)

    MAO Wei-min; ZHAO Ai-min; ZHANG Li-juan; ZHONG Xue-you

    2004-01-01

    The semisolid slurry preparation of die steels Cr12 and Cr12MoV with high chromium content was studied. The results show that the semisolid slurry of both steels with solid of 40 %-60 % can be made by electromagnetic stirring method and is easy to be discharged from the bottom little hole of the stirring chamber. The sizes of the spherical primary austenite in the slurry of die steels Cr12 and Cr12MoV are 50-100 μm and 80-150 μm, respectively. The homogeneous temperature field and solute field for both steel melts are obtained. The strong temperature fluctuation in the melt with many fine primary austenite grains occurs and the remelting of the secondary arm roots at the same time is accelerated because of the electromagnetic stirring. These are the most important reasons for deposition of spherical primary austenite grains.

  4. Chromium

    Science.gov (United States)

    ... health risks of too much chromium? Chromium and medication interactions Supplemental sources of chromium Chromium and Healthful Diets References Disclaimer What foods provide chromium? Chromium is widely distributed in the ...

  5. Low-chromium reduced-activation ferritic steels

    International Nuclear Information System (INIS)

    Steels are being developed for fusion-reactor applications that contain only elements that produce radioactive isotopes that decay to low levels in a reasonable time. These reduced-activation or fast induced-radioactivity decay ferritic steels are being developed to be analogous to the Cr-Mo steels presently in the fusion program, but with molybdenum replaced by tungsten. In this paper, steels with 2-1/4% Cr will be discussed. To determine the effect of tungsten and vanadium on these steels, heats were produced with 2% W, with 0.25% V, with 1% W and 0.25% V, and with 2% W and 0.25% V. Tempering and microstructural studies were made and tensile and impact tests were conducted. Preliminary results indicate that it should be possible to develop a low-chromium Cr-W steel without molybdenum or niobium. Such steels should have properties as good as or better than the three Cr-Mo steels presently being considered as candidates for fusion-reactor applications. 22 refs., 12 figs., 3 tabs

  6. Microstructure of a high boron 9-12% chromium steel

    Energy Technology Data Exchange (ETDEWEB)

    Andren, H.O. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Applied Physics

    2008-07-01

    Additions of small amounts of boron (10-100 ppm) to 9-12% chromium steels are often made since they have been found to be beneficial for the creep strength up to and above 600 C. The effect of boron is to restrict the coarsening of M{sub 23}C{sub 6} precipitates during service. It was found that increasing the boron content from 9 to 40 ppm gave a decrease in coarsening constant at 600 C by a factor of 2. The present understanding of boron solution, non-equilibrium grain boundary segregation, incorporation into M{sub 23}C{sub 6}, and diffusion is reviewed in the paper. A very high boron addition (300 ppm) was made in the trial TAF steel already in the 1950'ies. The microstructure of a similar trial steel, FT3B, has been studied detail. In this steel large Mo, Cr, Fe and V containing metal borides are formed rather than the expected BN, with the crystal structure M{sub 2}B{sub 2}. Nitrogen is therefore still available for the formation of VN. Due to tempering at a low temperature (690 C) to a high strength (830 MPa), this steel contained a dense distribution of very small VN precipitates, 5-15 nm in size. A similar VN distribution is probably the cause of the still unsurpassed creep strength of the TAF steel. (orig.)

  7. Boriding of high carbon high chromium cold work tool steel

    International Nuclear Information System (INIS)

    High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30 percentage B4C, 70 percentage borax at 950 degree C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 micro m. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc were test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time. (author)

  8. Boriding of high carbon high chromium cold work tool steel

    Science.gov (United States)

    Muhammad, W.

    2014-06-01

    High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30% B4C, 70% borax at 950 °C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 μm. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc wer test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time.

  9. Boriding of high carbon high chromium cold work tool steel

    International Nuclear Information System (INIS)

    High-carbon high-chromium cold work tool steels are widely used for blanking and cold forming of punches and dies. It is always advantageous to obtain an increased wear resistant surface to improve life and performance of these steels. In this connection boriding of a high-carbon high-chromium cold work die steel, D3, was conducted in a mixture of 30% B4C, 70% borax at 950 °C for two, four and six hours. Case depth of the borided layer obtained was between 40 to 80 μm. After boriding, the surface hardness achieved was between 1430 to 1544 HV depending upon the process time. X-ray diffraction studies confirmed the formation of a duplex compound layer consisting of FeB and Fe2B. It is generally considered that FeB is undesirable because of its inherent brittleness. Post boriding treatment (homogenization) transformed the compound layer into single-phase layer of Fe2B, while surface hardness decreased to 1345-1430 HV. Pin-on-disc wer test showed that wear resistance of the borided samples was superior as compared to non-borided material and increased with boriding time

  10. Chromium-nickel stainless steel and method of its manufacture

    International Nuclear Information System (INIS)

    The chromium-nickel stainless steel is designed for the production of rolled bands to be welded onto the primary circuit component surfaces. The invention claims the steel composition. Phosphorus content is restricted to an amount of 0.005 to 0.025%, sulfur to 0.001 to 0.012%, oxygen to 0.001 to 0.008% aluminium to 0.005 to 0.05%, and titanium to 0.02 to 0.20%. The steel may also contain 0.01 to 0.15% of cerium, 0.01 to 0.15% of zirconium and 0.0001 to 0.005% of boron while the overall combined content of cerium, zirconium and boron does not exceed 0.25%. The initial material is nonalloyed waste, nickel metal and ferroalloys. The steel is deoxidized with aluminium and its chemical composition is adjusted with an addition of ferrochrome or nickel. The steel is then vacuum processed and after standing, it is cast at a temperature of 1520 to 1580 degC. (J.P.)

  11. Chromium accumulation, microorganism population and enzyme activities in soils around chromium-containing slag heap of steel alloy factory

    Institute of Scientific and Technical Information of China (English)

    HUANG Shun-hong; PENG Bing; YANG Zhi-hui; CHAI Li-yuan; ZHOU Li-cheng

    2009-01-01

    The environmental risk of chromium pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by chromium. 45 soil samples obtained from different places of the slag heap in a steel alloy factory were analyzed for chromium contamination level and its effect on soil microorganisms and enzyme activities. The results show that the average concentrations of total Cr in the soil under the slag heap, adjacent to the slag heap and outside the factory exceed the threshold of Secondary Environmental Quality Standard for Soil in China by 354%, 540% and 184%, respectively, and are 15, 21 and 9 times higher than the local background value, respectively. Elevated chromium loadings result in changes in the activity of the soil microbe, as indicated by the negative correlations between soil microbial population and chromium contents. Dehydrogenase activity is greatly depressed by chromium in the soil. The results imply that dehydrogenase activity can be used as an indicator for the chromium pollution level in the area of the steel alloy factory.

  12. The oxidation and reduction of chromium of stainless steels in an eletric arc furnace

    Directory of Open Access Journals (Sweden)

    B. Arh

    2011-07-01

    Full Text Available The oxidation of chromium during the elaboration of stainless steels occurs with oxygen in solution blown inthe melt and with oxides in the slag. A higher content of silicon in the furnace charge decreases the extent of oxidation of chromium, however, the efficient reduction of chromium from the slag is of essential importance for a minimal loss of chromium. In this survey, the theory of the oxidation of chromium, its reduction from the slag and the conditions for the formation of foaming slag are discussed.

  13. Half life of chromium in serum and urine in a former plasma cutter of stainless steel

    OpenAIRE

    Petersen, R.; Thomsen, J. F.; Jorgensen, N. K.; Mikkelsen, S

    2000-01-01

    For 8 years chromium in serum and urine has been followed up in a former plasma cutter of stainless steel who was exposed to airborne dust and fumes containing chromium during this work. After the first examination for serum chromium the exposure ended. Serum chromium concentration has been measured seven times during the period and was initially very high and has subsequently dropped slowly. The half life was 40 months in serum. Urinary chromium has been measured five times. The half life wa...

  14. 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.

  15. Serum chromium levels sampled with steel needle versus plastic IV cannula. Does method matter?

    DEFF Research Database (Denmark)

    Penny, Jeannette Ø; Overgaard, Søren

    2010-01-01

    causing bias. This study aimed to test that theory. METHODS: We compared serum chromium values for two sampling methods, steel needle and IV plastic cannula, as well as sampling sequence in 16 healthy volunteers. RESULTS: We found statistically significant chromium contamination from the steel needle with...... mean differences between the two methods of 0.073 ng/mL, for the first sample, and 0.033 ng/mL for the second. No difference was found between the first and second plastic sample. The first steel needle sample contained an average of 0.047 ng/mL more than the second. This difference was only borderline...... significant. CONCLUSION: The chromium contamination from the steel needle is low, and sampling method matters little in MoM populations. If using steel needles we suggest discarding the first sample....

  16. Current Developments of Alloyed Steels for Hot Strip Roughing Mills : Characterization of High-Chromium Steel and Semi-High Speed Steel

    OpenAIRE

    LECOMTE-BECKERS, Jacqueline; Sinnaeve, Mario; Tchuindjang, Jérôme Tchoufack

    2012-01-01

    Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill - high chromium steel (HCS) and semi-high-speed steel (semi-HSS), In this paper, the new semi-high-speed steel grade is studied

  17. A comparison of low-chromium and high-chromium reduced-activation steels for fusion applications

    International Nuclear Information System (INIS)

    Ferritic steels have been considered candidate structural materials for first wall and blanket structures for fusion power plants since the late 1970s. The first steels considered in the United States were the conventional Cr-Mo steels Sandvik HT9 (nominally 12Cr-1Mo-0.25V-0.5W-0.5Ni-0.2C, here designated l2Cr-1MoVW), modified 9Cr-1Mo steel (9Cr-1Mo-0.2V-0.06Nb-0. IC, designated 9Cr-1MoVNb) and, to a lesser extent, 2 1/4Cr-1Mo steel (2.25Cr-Mo-0.1C). All compositions are in wt. %. The normalized-and-tempered 9 and 12Cr steels had a tempered martensite microstructure, and the normalized-and-tempered 2 1/4 Cr steel had a tempered bainite microstructure. This report describes chromium steels tested in normalized and tempered conditions. Miniature tensile and Charpy specimens were tested

  18. Corrosion resistance enhancement of SAE 1020 steel after Chromium implantation by nitrogen ion recoil

    OpenAIRE

    Geraldo Francisco Gomes; Mario Ueda; Antonio Fernando Beloto; Roberto Zenhei Nakazato; Helfried Reuther

    2005-01-01

    SAE 1020 construction steel is widely used as mortar reinforcement and small machine parts, but aside good surface properties as high ductility, hardness and wear resistance, its surface is prone to severe corrosion. As it is known, Chromium in amount over 12%-13% in the Fe alloys renders them resistance to several corrosive attacks. SAE 1020 samples were recovered with Chromium film and then bombarded either by nitrogen Ion Beam (IB) or Plasma Immersion Ion Implantation (PIII) to recoil impl...

  19. Is chromium from stainless steel utensils responsible for epidemic of type 2 diabetes?

    Science.gov (United States)

    Gambhir, Prakash S; Phadke, Mrudula A

    2011-07-01

    Type 2 diabetes prevalence is rising rapidly in developing world especially in India in last few decades. 'Thrifty phenotype' and 'westernization of lifestyle' is used to explain this epidemic. Chromium is an important modulator in insulin and glucose metabolism. Preconceptional chromium exposure has been demonstrated to raise the corticosterone and glucose levels in offspring of rodent model. Chromium is chelated when acidic food is stored in the stainless steel utensils. Chromium levels are shown to be high in Asian Indians. The hyperinsulinemia and insulin resistance is demonstrated in Indians from the newborn stage. We hypothesize that increased exposure to chromium in preconceptional and/or fetal stage leads to altered epigenetic control and altered endocrine and metabolic functioning. Increasing urbanization has led to increasing use of stainless steel and resultant exposure to chromium is at the least partly responsible for rising prevalence of type 2 diabetes. If proven avoiding or modifying the use of stainless steel utensils will halt the present epidemic of type 2 diabetes. PMID:21477931

  20. 76 FR 58536 - Tin- and Chromium-Coated Steel Sheet From Japan; Notice of Commission Determination To Conduct a...

    Science.gov (United States)

    2011-09-21

    ... FR 31633, June 1, 2011) were adequate. A record of the Commissioners' votes, the Commission's... COMMISSION Tin- and Chromium-Coated Steel Sheet From Japan; Notice of Commission Determination To Conduct a Full Five-Year Review Concerning the Antidumping Duty Order on Tin- and Chromium-Coated Steel...

  1. The Interpretation of Experimental Observation Data for the Development of Mechanisms based Creep Damage Constitutive Equations for High Chromium Steel

    OpenAIRE

    Yang, Xin; Lu, Zhongyu; Xu, Qiang

    2015-01-01

    It is very important to design a safe factor or estimating the remain lifetime for electric power plant components of steam pipes which mostly manufacture by high chromium steels and work at high temperature and low stress level. The author will develop the mechanisms based on creep damage constitutive equations for high chromium steel under lows stress in initial stage: (1) Creep cavities mostly formed attaching with the precipitation of Laves phase or on grain boundary for high chromium ste...

  2. Electrochemical characterization of oxide formed on chromium containing mild steel alloys in LiOH medium

    International Nuclear Information System (INIS)

    Flow accelerated corrosion leads to wall thinning of outlet-feeder pipes in the primary heat transport system of pressurized heavy water reactors and can even necessitate enmasse feeder replacement. Replacement of carbon steel 106-grade-B (CS) with chromium containing carbon steel reduces the risk of this failure. This paper discusses the role of small additions of chromium in modifying the properties of the oxide film. CS and chromium containing mild steels viz., A333, 2.25Cr–1Mo and modified 9Cr–1Mo alloy were exposed to primary heat transport (PHT) system chemistry conditions. The oxide films formed were characterized by electrochemical and surface characterization techniques. Mott–Schottky analysis showed donor type of defects. The densities of defects in the oxides of chromium containing alloys were 3–15 times less than that in CS. In presence of ∼200 ppb of dissolved oxygen, the oxides formed were hematite with two orders of magnitude smaller concentration of defects as compared to that formed under reducing conditions. These results suggest that the presence of chromium lowers the defect density of the oxide film and thus ensures a reduced corrosion rate. - Graphical abstract: Display Omitted - Highlights: • High temperature oxides formed on Cr containing mild steels are less defective. • Defect densities of oxides decrease with increase in Cr content in the alloy. • O2 in solution greatly influences the nature and defect chemistry of oxides

  3. Creep strength and ductility of 9 to 12% chromium steels

    DEFF Research Database (Denmark)

    Hald, John

    2004-01-01

    Steels", which covers creep data development and analysis for parent materials and welds of all ferritic creep resistant steels ranging from low alloy steels up to 12%Cr steels. The opinions stated in the paper represent the views of the author rather than the whole ECCC WG3A group.......The present paper focuses in on long-term creep properties of parent material of the new 9-12%Cr creep resistant steels, P91, E911 and P92 developed for use in advanced ultrasupercritical power plants. These steels have been at the center of activities in the ECCC Working Group 3A (WG3A) "Ferritic...

  4. Creep strength and ductility of 9 to 12% chromium steels

    DEFF Research Database (Denmark)

    Hald, John

    2004-01-01

    The present paper focuses in on long-term creep properties of parent material of the new 9-12%Cr creep resistant steels, P91, E911 and P92 developed for use in advanced ultrasupercritical power plants. These steels have been at the center of activities in the ECCC Working Group 3A (WG3A) "Ferritic...... Steels", which covers creep data development and analysis for parent materials and welds of all ferritic creep resistant steels ranging from low alloy steels up to 12%Cr steels. The opinions stated in the paper represent the views of the author rather than the whole ECCC WG3A group....

  5. Nonequilibrium grain-boundary cosegregation of nitrogen and chromium in NiCrMoV steel

    Science.gov (United States)

    Zheng, Lei; Xu, Tingdong

    2005-12-01

    It is concluded in this article that nonequilibrium grain-boundary cosegregation (NCGS) of nitrogen and chromium occurs in NiCrMoV steel. That conclusion is reached from experimental observations of the parallel segregation isotherms and the maximum coverage of Cr and N at grain boundaries during the isotherms. This means that the nonequilibrium segregation of Cr induces that of N, in NiCrMoV steel.

  6. Recommended practices for welding of chromium-molybdenum steel piping and tubing

    International Nuclear Information System (INIS)

    This book contains recommendations for welding chromium-molybdenum steel pipe and tubing to itself and to various other materials. Subjects covered in detail are filler metal selection, joint design, preheating, and postheating. Particular emphasis is placed on the importance of maintaining interpass temperature and dangers inherent in interrupted heating cycles

  7. Activities of chromium oxides in slag in the process of argon-oxygen refining of corrosion-resistant steel

    International Nuclear Information System (INIS)

    On the basis of computer simulation results and available experimental data the behaviour of chromium oxides on stainless steel refining is studied. It is revealed that during melting and argon-oxygen refining of stainless steels chromium oxides occur in the solution if the slag contains not more than 25% (by mass) Cr2O3; this fact generates a need for accounting chromium oxide activity in thermodynamic calculations. An increase of Cr2O3 activity in the slag of this type results in increasing percentage ratio of chromium and carbon in the metal

  8. Investigation of strength of austenitic nitrogen-containing chromium-nicel-manganese steels at cryogenic temperature

    International Nuclear Information System (INIS)

    The mathematical method of experiment planning based on experimental data, analysis of regressive dependences with application of computerized graphics is used to optimize composition of the chromium-nickel-manganese high-strength steel with nitrogen and molybdenum to work under cryogenic temperatures. N, Ni, Mn, Mo and Cr are determined for their effect on the strength characteristics (σB and σ0.2) at the test temperatures of 293, 77, 20 K. Alloying elements are also studied for their effect on low-temperature steel hardening. Experimental and calculated data are verified by results from testing steels of chemical composition

  9. Creep and creep-fatigue behavior of high chromium steel weldment

    Institute of Scientific and Technical Information of China (English)

    Yukio TAKAHASHI; Masaaki TABUCHI

    2011-01-01

    Manuscript received I December 2010; in revised form 9 March 2011Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensile hold have been carried out on the welded joints of two types of high chromium steels widely used in Japan, I.e. Grade 91 and 122 steels. It was found that failure occurred in fine grain heat-affected zone in all the creep-fatigue tests, even at a relatively low temperature and fairly short time where failure occurred in plain base metal region in simple creep testing. Four procedures were used to predict failure lives and their results were compared with the test results. A newly proposed energy-based approach gave the best estimation of failure life, without respect of the material and temperature.

  10. Chromium-molybdenum steels for fusion-reactor applications

    International Nuclear Information System (INIS)

    Because ferritic steels have been found to have excellent resistance to swelling when irradiated in a fast-breeder reactor, Cr-Mo steels have recently become of interest for nuclear applications, both as cladding and duct material for fast-breeder reactors and as a first-wall and blanket structural material for fusion reactors. In this paper we will assess the Cr-Mo steels for fusion reactor applications. Possible approaches on how Cr-Mo steels may be further developed for this application will be proposed

  11. Adsorption and protein-induced metal release from chromium metal and stainless steel.

    Science.gov (United States)

    Lundin, M; Hedberg, Y; Jiang, T; Herting, G; Wang, X; Thormann, E; Blomberg, E; Wallinder, I Odnevall

    2012-01-15

    A research effort is undertaken to understand the mechanism of metal release from, e.g., inhaled metal particles or metal implants in the presence of proteins. The effect of protein adsorption on the metal release process from oxidized chromium metal surfaces and stainless steel surfaces was therefore examined by quartz crystal microbalance with energy dissipation monitoring (QCM-D) and graphite furnace atomic absorption spectroscopy (GFAAS). Differently charged and sized proteins, relevant for the inhalation and dermal exposure route were chosen including human and bovine serum albumin (HSA, BSA), mucin (BSM), and lysozyme (LYS). The results show that all proteins have high affinities for chromium and stainless steel (AISI 316) when deposited from solutions at pH 4 and at pH 7.4 where the protein adsorbed amount was very similar. Adsorption of albumin and mucin was substantially higher at pH 4 compared to pH 7.4 with approximately monolayer coverage at pH 7.4, whereas lysozyme adsorbed in multilayers at both investigated pH. The protein-surface interaction was strong since proteins were irreversibly adsorbed with respect to rinsing. Due to the passive nature of chromium and stainless steel (AISI 316) surfaces, very low metal release concentrations from the QCM metal surfaces in the presence of proteins were obtained on the time scale of the adsorption experiment. Therefore, metal release studies from massive metal sheets in contact with protein solutions were carried out in parallel. The presence of proteins increased the extent of metals released for chromium metal and stainless steel grades of different microstructure and alloy content, all with passive chromium(III)-rich surface oxides, such as QCM (AISI 316), ferritic (AISI 430), austentic (AISI 304, 316L), and duplex (LDX 2205). PMID:22014396

  12. The electrochemistry of 13% chromium stainless steel in oilfield brines

    Energy Technology Data Exchange (ETDEWEB)

    Sidorin, Dmitry; Pletcher, Derek [Department of Chemistry, The University of Southampton, Southampton SO17 1BJ (United Kingdom); Hedges, Bill [BP Trinidad Ltd., P.O. Box 714, Port of Spain (Trinidad and Tobago)

    2005-07-25

    The electrochemistry of a 13% Cr stainless steel (API5CT L80-13Cr) in 3% NaCl containing acetate and either acetic acid or carbon dioxide at 333 K is explored using RDE voltammetry. The reduction of proton, carbonic acid and acetic acid occur simultaneously, immediately negative to the corrosion potential. Acetic acid gives a well formed reduction wave and the current densities increase with the equilibrium concentration of acetic acid in the medium; in the plateau region, the reduction is mass transport controlled. Despite this reduction process, the corrosion resistance and passivation current density are independent of the acetic acid concentration. It is confirmed that the 13% Cr stainless steel is much more resistant to corrosion that X65 carbon steel and, unlike the carbon steel, its rate of corrosion does not vary with acetic acid concentration. The properties of the passivating film appear to dominate the behaviour of the 13% Cr stainless steel. (author)

  13. The electrochemistry of 13% chromium stainless steel in oilfield brines

    International Nuclear Information System (INIS)

    The electrochemistry of a 13% Cr stainless steel (API5CT L80-13Cr) in 3% NaCl containing acetate and either acetic acid or carbon dioxide at 333 K is explored using RDE voltammetry. The reduction of proton, carbonic acid and acetic acid occur simultaneously, immediately negative to the corrosion potential. Acetic acid gives a well formed reduction wave and the current densities increase with the equilibrium concentration of acetic acid in the medium; in the plateau region, the reduction is mass transport controlled. Despite this reduction process, the corrosion resistance and passivation current density are independent of the acetic acid concentration. It is confirmed that the 13% Cr stainless steel is much more resistant to corrosion that X65 carbon steel and, unlike the carbon steel, its rate of corrosion does not vary with acetic acid concentration. The properties of the passivating film appear to dominate the behaviour of the 13% Cr stainless steel

  14. Liquid Phase Sintering of Boron-Containing Powder Metallurgy Steel with Chromium and Carbon

    Science.gov (United States)

    Wu, Ming-Wei; Fan, Yu-Chi; Huang, Her-Yueh; Cai, Wen-Zhang

    2015-11-01

    Liquid phase sintering is an effective method to improve the densification of powder metallurgy materials. Boron is an excellent alloying element for liquid phase sintering of Fe-based materials. However, the roles of chromium and carbon, and particularly that of the former, on liquid phase sintering are still undetermined. This study demonstrated the effects of chromium and carbon on the microstructure, elemental distribution, boride structure, liquid formation, and densification of Fe-B-Cr and Fe-B-Cr-C steels during liquid phase sintering. The results showed that steels with 0.5 wt pct C densify faster than those without 0.5 wt pct C. Moreover, although only one liquid phase forms in Fe-B-Cr steel, adding 0.5 wt pct C reduces the formation temperature of the liquid phase by about 50 K (°C) and facilitates the formation of an additional liquid, resulting in better densification at 1473 K (1200 °C). In both Fe-B-Cr and Fe-B-Cr-C steels, increasing the chromium content from 1.5 to 3 wt pct raises the temperature of liquid formation by about 10 K (°C). Thermodynamic simulations and experimental results demonstrated that carbon atoms dissolved in austenite facilitate the eutectic reaction and reduce the formation temperature of the liquid phase. In contrast, both chromium and molybdenum atoms dissolved in austenite delay the eutectic reaction. Furthermore, the 3Cr-0.5Mo additive in the Fe-0.4B steel does not change the typical boride structure of M2B. With the addition of 0.5 wt pct C, the crystal structure is completely transformed from M2B boride to M3(B,C) boro-carbide.

  15. Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline

    Directory of Open Access Journals (Sweden)

    LI Wei

    2007-02-01

    Full Text Available A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303g/L NaOH alkaline solution at 85℃ was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experimental results showed that protection effect by passive film of cast steel containing Cr was temporary. The low carbon steel without Cr content also exhibited chemical passivity in the same solution. The corrosion mode of the tested Cr-containing cast steel was composed of active dissolving corrosion and caustic embrittlement cracking. Dissolving corrosion was the primary mechanism for the induced weight loss, while severe caustic embrittlement cracking was secondary. With the increase of chromium content in the cast steel, the tendency of the caustic embrittlement cracking decreased, while the active dissolving corrosion increased.

  16. Corrosion resistance of high-chromium steels in coal gasification atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Kihara, S.; Nakagawa, K.; Ohtomo, A.; Kato, M.

    1987-06-01

    The corrosion resistances of AISI 347H and 310 stainless steels (SSs), 35Cr-45Ni steel, and chromized and aluminized AISI 347H SS were evaluated in simulated coal gasification atmospheres at 550, 600, and 650 C. The scales formed were mainly sulfides, with a small amount of oxides. Although the corrosion of AISI 347H and 310 SS increased with increasing temperature the corrosion of high-chromium steels, 35Cr-45Ni steel, and chromized AISI 347H SS remarkably decreased at 650 C. Weight gain decreased with increasing chromium content of steel. However, local corrosion occurred on 35Cr-45Ni steel at 600 C. The aluminized samples were the most corrosion resistant of the materials tested, but some cracks were found in the aluminized layer after 100-h exposure. Addition of HCI to the simulated gasification atmosphere generally accelerated corrosion by the formation of a porous outer scale. Pitting during downtime corrosion occurred only for AISI 347H SS exposed in the simulated gas involving 0.2 vol% HCI. The results of electrochemical measurements suggested that the downtime corrosion might by polythionic acid corrosion and crevice corrosion in the solution involving CI/sup -/.

  17. Corrosion of two kinds of cast steels containing chromium in hot concentrated alkaline

    Institute of Scientific and Technical Information of China (English)

    LI Wei; LIU Jun-quan; TU Xiao-hui

    2007-01-01

    A typical hot concentrated alkaline corrosion environment exists in alumina metallurgical industry, so that steel materials with outstanding alkaline corrosion resistance are strongly demanded for its processing equipment. In this paper, the corrosion resistance of two kinds of martensitic cast steels containing chromium in static 303 g/L NaOH alkaline solution at 85℃ was studied through polarization and potential-time curves, corrosion weight loss and corrosion morphology analysis. Experimental results showed that protection effect by passive film of cast steel containing Cr was temporary. The low carbon steel without Cr content also exhibited chemical passivity in the same solution. The corrosion mode of the tested Cr-containing cast steel was composed of active dissolving corrosion and caustic embrittlement cracking. Dissolving corrosion was the primary mechanism for the induced weight loss, while severe caustic embrittlement cracking was secondary. With the increase of chromium content in the cast steel, the tendency of the caustic embrittlement cracking decreased, while the active dissolving corrosion increased.

  18. The relationship between microstructure and mechanical properties of ferritic chromium steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Mayr, Peter; Cerjak, Horst [Graz Univ. of Technology (Austria); Toda, Yoshiaki; Hara, Toru; Abe, Fujio [National Institute for Materials Science (Japan)

    2008-07-01

    Welding as the major joining and repair technology for steels in thermal power plants has a significant influence on the steels microstructure and, therefore, on its properties. Heat-resistant martensitic 9-12% chromium steels show an affinity to the retention of delta ferrite in the heat-affected zone of their weldments. This is related to their high level of ferrite stabilizing alloying elements such as Cr, W or Mo. Retained delta ferrite in martensitic steel grades has a significant negative influence on creep strength, fatigue strength, toughness and oxidation resistance. In the long-term range of creep exposure, many weldments of martensitic heatresistant steels fail by Type IV cracking in the fine-grained region of the heat-affected zone. In this work, the formation of the heat-affected zone microstructures in martensitic chromium steels is studied by in-situ X-ray diffraction using synchrotron radiation, optical microscopy as well as most advanced electron microscopical methods. The observed microstructure is directly linked to the mechanical properties, i.e. ductility, toughness and creep strength. Characteristic failure modes are discussed in detail. (orig.)

  19. Effect of Chromium Ion Implantation on the Oxidation Rate of Iron andSteel

    International Nuclear Information System (INIS)

    This research discussed about the effect of chromium ion implantation onthe oxidation rate of iron (Fe 95.5 %) and steel (AISI 304). The measurementof oxidation resistance of the samples was carried out in dry oxygen mediumat high temperature conditions and the time of observation was varied. Theoxidation resistance can be analyzed by the changing of weight before andafter the process. The result showed that for iron materials (Fe 95.5 %)implanted chromium ion at energy 100 keV and ion dose 5 x 1017 ion/cm2increase the oxidation resistance in order of 28.68 %. But for AISI 304 steelimplanted chromium ion at the same conditions, the oxidation resistancedecreased. This phenomena is caused by the fact that the content of chromiummaybe already exceed the solubility of base material and it will create thepossibility of the formation of oxid spinel which less protective. (author)

  20. Ionic nitriding of high chromium martensitic stainless steels

    International Nuclear Information System (INIS)

    Martensitic stainless steels are used in industrial applications where resistance to corrosion and mechanical resistance are needed simultaneously. These steels are normally used in tempering and annealing condition which gives them hardnesses of 500 and 600 HV (about 54 HRC). Ionic nitriding is an assisted diffusion technique that has recently been successfully applied to harden austenitic stainless steels without reducing their resistance to corrosion. The application with AISI 420 martensitic steels has not given good results yet, because in most cases, it affects their corrosion resistance. This work presents the results of the pulsed nitriding of martensitic steels with a higher chrome content, such as the M340 and M333 Boehler steels and they are compared with the same materials after tempering and annealing, without nitriding. The influence of the variations in the parameters of the process, such as the percentage of active time in the pulsed wave, partial nitrogen pressure, current density and effective tension in the microstructure, hardness and wear and corrosion resistance was studied. The microstructure was studied with an optic microscope; the wear resistance with abrasion tests following ASTM G-65 and corrosion with 100 hour long saline haze tests, in a device built according to ASTM B117. Hardness was found to rise to values of 1000 to 1350 HV in all the steels after ionic nitriding, the modified layers oscillated from 3 to 15 microns. As a result, wear resistance also increased, with differences depending on the microstructure and the thickness of the modified layer. However, corrosion resistance was not good, except in the case of the M333 steel test piece with less hardness and a less thick nitrided layer without a noticeable interphase (au)

  1. Optimum tungsten content in high strength 9 to 12% chromium containing creep resistant steels

    International Nuclear Information System (INIS)

    Tungsten containing ferritic creep resistant steels are the candidate materials for ultra-super-critical fossil power plant because of their high creep rupture strength. But the strengthening mechanisms by tungsten addition have not yet been completely studied. In this report, creep rupture time and creep strain rate measurement decided the optimum tungsten content in 9 to 12% chromium ferritic steels. The precipitation behavior of Laves phase and the precise discussion of creep strain rate analyses explain the contribution of Laves phase at the lath boundary and the contribution of tungsten in solid solution. P92 contains the optimum amount of tungsten and chromium, 1.8 mass% and 9 mass% respectively judging from the creep rupture strength point of view. (orig.)

  2. Considerations upon the cavitation erosion resistance of stainless steel with variable chromium and nickel content

    Energy Technology Data Exchange (ETDEWEB)

    Karabenciov, A; Jurchela, A D; Bordeasu, I; Birau, N; Lustyan, A [Department of Hydraulic Machinery, ' Politehnica' University of Timisoara, Bv. Mihai Viteazu, no. 1, Timisoara, 300222 (Romania); Popoviciu, M, E-mail: karabenciov@yahoo.co [Academy of Romanian Scientists, Timisoara Branch (Romania)

    2010-08-15

    Paper presents results of experimental investigations regarding the cavitation erosion of eight different stainless steels with constant carbon content (0.1%). Four of them have constant chromium (12%) and variable nickel content. The other four have constant nickel (10%) and variable chromium content. Using the images of the eroded specimens, the parameters MDPR and MDP as well as the characteristic curves, the influence of chemical and structural modifications, upon the cavitation erosion, are put into evidence. The investigated steels, manufactured through casting, maintain the general composition of the materials with good cavitation erosion qualities. The experimental researches were carried out in Timisoara Hydraulic Machinery Laboratory on a magnetostrictive facility, taking into account the ASTM G32-2008 Standards.

  3. The compatibility of chromium-aluminium steels with high pressure carbon dioxid at intermediate- temperatures

    International Nuclear Information System (INIS)

    With a view to their use in the exchangers of nuclear reactors of the graphite-gas or heavy water-gas types, the behaviour of chromium-aluminium steels containing up to 7 per cent chromium and 1.5 per cent aluminium has been studied in the presence of high-pressure carbon dioxide at temperatures of between 400 and 700 deg. C. The two most interesting grades of steel (2 per cent Cr - 0.35 per cent Al - 0.35 per cent Mo and 7 per cent Cr - 1.5 per cent Al - 0.6 per cent Si) are still compatible with carbon dioxide up to 550 and 600 deg. C respectively. A hot dip aluminised coating considerably increases resistance to oxidation of the first grade and should make possible its use up to temperatures of at least 600 deg. C. (authors)

  4. Chromium martensitic hot-work tool steels : damage, performance and microstructure

    OpenAIRE

    Sjöström, Johnny

    2004-01-01

    Chromium martensitic hot-work tool steel (AISI H13) is commonly used as die material in hot forming techniques such as die casting, hot rolling, extrusion and hot forging. They are developed to endure the severe conditions by high mechanical properties attained by a complex microstructure. Even though the hot-work tool steel has been improved over the years by alloying and heat treatment, damages still occur. Thermal fatigue is believed to be one of the most common failure mechanisms in hot f...

  5. RECENT TRENDS IN HOT STRIP ROUGHING MILLS: HIGH CHROMIUM STEEL VERSUS SEMI-HSS

    OpenAIRE

    Lecomte-Beckers, Jacqueline; Tchuindjang, Jérôme Tchoufack; Sinnaeve, Mario; Ernst, Roger

    2010-01-01

    compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new grade developed to improve the overall performance of the work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade is studied starting from three chemical compositions closed one to another, the variation in the alloying elements is intended to asse...

  6. Comparison between High Chromium Steel and Semi HSS used in Hot Strip Mill Roughing Stands

    OpenAIRE

    Lecomte-Beckers, Jacqueline; Sinnaeve, Mario; Tchuindjang, Jérôme Tchoufack

    2011-01-01

    Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) are compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new grade developed to improve the overall performance of the work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade is studied starting from three chemical compositions closed o...

  7. Study of corrosion resistance of chromium-nickel steel in calcium - hypochlorite solution. Part 1. Steels uranus b6

    Directory of Open Access Journals (Sweden)

    Tošković D.

    2002-01-01

    Full Text Available Corrosion resistance of Cr - Ni (special steels specimen is tested by electrochemical methods, numerical method of linear polarization and polarization resistance method in calcium-hypochlorite (Ca(OCl2 solutions. With increasing of Ca(OCl2 concentration, pH value of the solution increases, as well as active chlorine concentration and corrosion activity of the medium. According to the quantitative method of the corrosion resistance determination it can be concluded that the steels tested in 1 wt % Ca(OCl2 solution are resistant, in 10 wt % solution constant, and in 50 wt % suspension less resistant. URANUS B6 showed the best corrosion resistance of all tested chromium - nickel steels in all tested corrosion mediums.

  8. Remanent life assessment of creep resistant modified 12% chromium steels: microstructural analysis and microstructural development models

    Energy Technology Data Exchange (ETDEWEB)

    Lundin, L.; Andren, H.O. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Physics; Norell, M.; Nyborg, L. [Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

    1996-09-01

    In this report, an overview of the current status of the development work, physical metallurgy and creep properties of 9-12% chromium steels is given. These steels find their application mainly in the power generating industry, at high temperatures. In Sweden, a co-operation between research groups specialized at microanalysis and modelling of 9-12% chromium steels has been initiated. This co-operation is outlined in this report, as well as the most important results achieved so far. The microstructure of four different alloys have been studied in detail with different analytical methods including atom-probe field-ion microscopy, electron microscopy and Auger electron spectroscopy. The role of different elements on precipitation processes and the composition of all relevant phases have been studied. Furthermore, segregation of impurity elements to creep cavities and creep fracture surfaces have been studied for two of the alloys. Models for the microstructural development of 9-12% chromium steels during heat treatment and creep testing are currently being produced. The work has been focused on modelling the nucleation and growth of MN and M{sub 23}C{sub 6} precipitates during tempering, and the first results from these studies are currently being compared to microscopy observation. In addition, equilibrium phase calculations have been made and been found to predict existing phases to a high degree. A complete description of the creep properties of these steels must also include a model of the relationship between microstructure and creep behaviour. However, the microstructural development models will form an important basis for complete models of this kind. 57 refs

  9. Sorption of iodine on low-chromium-alloy steel

    International Nuclear Information System (INIS)

    The sorption behavior of iodine on the surfaces of 2 1/4% Cr-1% Mo steel was investigated as a part of the High Tmeperature Gas-Cooled Reactor (HTGR) Chemistry Program at Oak Ridge National Laboratory (ORNL). The primary objective of these tests was to determine the equilibrium sorptive capacity of this alloy, which comprises most of the cooler regions of HTGR coolant circuit, under representative conditions. The data will be used to improve the capability for predicting, with computer programs, iodine deposition as functions of temperature and location in the primary circuit

  10. Metallurgical and mechanical tests on the low activating martensitic chromium steel OPTIFER-IV

    International Nuclear Information System (INIS)

    Derived from a martensitic chromium-steel (1.4914) with high strength at elevated temperatures, a new low activating steel OPTIFER-IV, Chg. 986489, had been developed for an application as 'First Wall' - and as structural material for fusion devices. The alloying elements with high activation like Mo, Ni and Nb had been substituted by similar acting, but low activating elements like W and Ta. Some metallurgical and mechanical properties had been tested in order to decide the kind of alloying. The new steel is fully martensitic without δ-ferrite, fine-grained and well hardenable. The tensile properties satisfy the requirements, and the notch impact bending properties are excellent. (orig.)

  11. 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.

  12. Autowave process of the localized plastic deformation of high-chromium steel saturated with hydrogen

    Science.gov (United States)

    Bochkareva, A. V.; Barannikova, S. A.; Li, Yu V.; Lunev, A. G.; Zuev, L. B.

    2016-06-01

    The deformation behavior of high-chromium stainless steel of sorbitic structure upon high-temperature tempering and of electrically saturated with hydrogen in the electrochemical cell during 12 hours is investigated. The stress-strain curves for each state were obtained. From the stress-strain curves, one can conclude that hydrogen markedly reduces the elongation to the fracture of specimen. Using double-exposed speckle photography method it was found that the plastic flow of the material is of a localized character. The pattern distribution of localized plastic flow domains at the linear hardening stage was investigated. Comparative study of autowave parameters was carried out for the tempered steel as well as the electrically saturated with hydrogen steel.

  13. Study of corrosion resistance of chromium-nickel steel in calcium-hypochlorite solution part 2: Steels Č 4574 and Č 4583

    Directory of Open Access Journals (Sweden)

    Tošković D.

    2003-01-01

    Full Text Available This paper shows the results of investigations of corrosion resistance of different samples of chromium-nickel steels Č 4574 and Č 4583 in calcium-hypochlorite solution, by potentiodynamic method. The paper presents continuation of investigations on steels URANUS B6 and Č 4578 published in reference [1]. In this paper comparison of the obtained results is carried out, too, in order to detect steel, which quality is the best choice for calcium hypo chlorite solution requirements.

  14. A study on Z-phase nucleation in martensitic chromium steels

    DEFF Research Database (Denmark)

    Golpayegani, Ardeshir; Andrén, Hans-Olof; Danielsen, Hilmar Kjartansson;

    2008-01-01

    9–12% chromium martensitic steels are liable to the precipitation of Z-phase, Cr(V,Nb)N, after long time exposure at 550–650 ◦C. This complex nitride consumes vanadium nitrides and causes the creep strength of the material to fall drastically after several thousand hours of exposure. In this work....... Furthermore, such a nucleation site would provide vanadium and nitrogen for the growth of Z-phase. The presence of niobium carbide has also been observed close to Z-phase nucleation sites, indicating niobium to be important for the nucleation and growth of Z-phase....

  15. Effect of Rare Earth Elements on Thermal Fatigue Property of Low Chromium Semi-Steel

    Institute of Scientific and Technical Information of China (English)

    常立民; 刘建华; 张瑞军; 邵利; 于升学; 谌岩

    2003-01-01

    The effect of rare earth elements on eutectic carbide′s morphology of low chromium semi-steel in as-cast state and after heat treatment was investigated, and accordingly, the thermal fatigue property of this material was studied. The results show that RE can improve the eutectic carbide′s morphology, inhibit the formation and propagation of thermal fatigue cracks, therefore, promote the thermal fatigue property, which is more noticeable in case of the RE modification in combination with heat treatment. The optimal thermal fatigue property can be obtained when treated with 0.2% RE modification as well as normalization at 950 ℃ for 3 h.

  16. 76 FR 77013 - Tin- and Chromium-Coated Steel Sheet From Japan; Scheduling of a Full Five-Year Review Concerning...

    Science.gov (United States)

    2011-12-09

    ...-year review were such that a full review pursuant to section 751(c)(5) of the Act should proceed (76 FR... COMMISSION Tin- and Chromium-Coated Steel Sheet From Japan; Scheduling of a Full Five-Year Review Concerning... of the antidumping duty order on tin- and chromium-coated steel sheet from Japan would be likely...

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

    International Nuclear Information System (INIS)

    The microstructures of a 9Cr-2W-0.25-0.1C (9Cr-2WV), a 9Cr-2W-0.25V-0.07Ta-0.1C (9Cr-2WVTa), a 7Cr-2W-0.25V-0.07Ta-0.1C (7Cr-2WVTa), and a 5Cr-2W-0.25V-0.07Ta-0.1C (5Cr-2WVTa) steel (all compositions are in weight percent) have been characterized by Analytical Electron Microscopy (AEM) and Atom Probe Field Ion Microscopy (APFIM). The matrix in all four reduced-activation steels was 100% martensite. In the two 9Cr steels, the stable precipitates were blocky M23C6 and small spherical MC. The two lower-chromium steels contained blocky M7C3 and small needle-shaped carbonitrides in addition to M23C6. AEM and APFIM analysis revealed that in the steels containing tantalum, the majority of the tantalum was in solid solution. The experimental observations were in good agreement with phases and compositions predicted by phase equilibria calculations

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1997-08-01

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

  19. Examinations on the morphology of tarnish layers grown on stainless 18-10 chromium nickel steels

    Energy Technology Data Exchange (ETDEWEB)

    Pajonk, G. [Staatliches Materialpruefungsamt Nordrhein-Westfalen, Dortmund (Germany); Bubert, H. [Inst. of Spectrochemistry and Applied Spectroscopy, Dortmund (Germany)

    1999-10-01

    18-10 chromium nickel steels are generally valid as well weldable. However, during thermal joining oxides are formed in the heat affected zone, whose structure and composition essentially differs from the morphology of passive layers. The steel qualities X6 CrNiTi 18-10 (materials no. 1.4541) and X5 CrNiMoTi 17-12-2 (materials no. 1.4571) were examined on their tarnish growing behaviour by means of XPS/sputtering, transmission electron microscopy and atomic force microscopy. Information on the pitting corrosion resistance of annealed metal sheets was received by ageing them in iron chloride solution and by measuring the current density-potential curves under quasi-stationary conditions in artificial sea water. (orig.)

  20. Aluminium effect on steel with 12%-chromium and various manganese contents

    International Nuclear Information System (INIS)

    To increase heat resistance, aluminium has been added to medium-carbon chromium-manganese steels, and its effect on the phase composition and microstructure has been studied. The investigation of alloys has been carried out over polythermal sections of the five-component Fe-C-Cr- Mn system at the constant carbon, chromium and aluminium content and cariable concentrations of manganese in the range of 1150 - 650 deg C. To study phase and structure transformations of alloys at high temperatures, the structure-hardening method has been used. The hardness of alloys containing to 12.6% of manganese appreciably depends on the quenching temperature. It is substantially higher in the original alloy quenched at high temperatures compared to the quenching at lower temperatures. It is due to the transition of its base from martensite-ferrite to ferrite state at 1000 deg C. The results obtained and the data of x-ray diffraction analysis allow a polythermal section of the Fe-C-Cr-Mn-Al system to be constructed at the constant 12%-chromium content, 2.4%-aluminium, 0.37%-carbon and variable manganese contents

  1. Effect of chromium, tungsten, tantalum, and boron on mechanical properties of 5-9Cr-WVTaB steels

    International Nuclear Information System (INIS)

    The Cr-W-V-Ta reduced-activation ferritic/martensitic steels use tungsten and tantalum as substitutes for molybdenum and niobium in the Cr-Mo-V-Nb steels that the reduced-activation steels replaced as candidate materials for fusion applications. Studies were made to determine the effect of W, Ta, and Cr composition on the tensile and Charpy properties of the Cr-W-V-Ta; steels with 5%, 7%, and 9% Cr with 2% or 3% W and 0%, 0.05%, or 0.10% Ta were examined. Boron has a long history of use in steels to improve properties, and the effect of boron was also examined. Regardless of the chromium concentration, the steels with 2% W and 0.05-0.1% Ta generally had a better combination of tensile and Charpy properties than steels with 3% W. Boron had a negative effect on properties for the 5% and 7% Cr steels, but had a positive effect on the 9% Cr steel. When the 5, 7, and 9Cr steels containing 2% W and 0.05% Ta were compared, the tensile and Charpy properties of the 5 and 9Cr steels were better than those of the 7Cr steel, and overall, the properties of the 5Cr steel were better than those of the 9Cr steel. Such information will be useful if the properties of the reduced-activation steels are to be optimized

  2. The role of interstitial nitrogen in the precipitation hardening reactions in high-chromium ferritic steels

    International Nuclear Information System (INIS)

    The effects of exposure to temperatures in the range 475 - 800 C on the hardness and associated microstructure of high chromium ferritic steels has been investigated. Low-carbon 26Cr-1Mo steels containing 0,02 - 0,04% nitrogen were found to constitute an age hardening system when quenched from a temperature of nitrogen solubility and exposed at temperatures in the range 600 - 700 C. TEM observations on thin foils revealed that hardening was associated with the formation of a high density of Cr-N zones. Ageing at 475 C and 550 C produced hardening due to the formation of chromium-rich ferrite phases α' as result of the miscibility gap in the Fe-Cr phase diagram. However the presence of interstitial nitrogen in solution in the steel considerably reduced the rate of hardening, especially at 475 C. This type of decomposition occurs by a mechanism of nucleation and growth, forming zones similar to those formed during an ageing at 600 C. When depleted of interstitial nitrogen, the specimens aged at 475 C underwent spinodal decomposition. Thus nitrogen in solid solution was found to have a significant effect on the 475 C hardening reaction. Precision X-ray diffraction measurements revealed the presence of secondary diffraction peaks associated with the Bragg peaks, which confirmed the formation of Cr-rich phases during ageing at 475 C. The calculated associated lattice parameter measurements allowed estimates of the compositions of the decomposition phases to be made. These were calculated to be about 6-18% Cr in the Fe-rich and 60-80% Cr in the Cr-rich phases of the 26Cr-1Mo steel

  3. Behaviour of the 9% chromium steel P 9 1 and its weldments in short and long term tests

    Energy Technology Data Exchange (ETDEWEB)

    Bruhl, F.; Haarmann, K.; Kalwa, G.; Weber, H. (Mannesmann-Concern, Dusseldorf (DE)); Cerjak, H. (Technical Univ., Graz (AT)); Musch, H. (Vereinigte Elektrizitatswerke, Hamm (DE)); Niederhoff, K.; Wellnitz, G.; Zschau, M. (Mannesmann-Concern, Dusseldorf (DE))

    1990-01-01

    A new 9% chromium ferritic steel, currently identified as Grade 9 1 in ASTM/ASME specification, has been developed in the USA as a result of extensive research since 1975. The new steel was intended for applications involving temperatures as high as 650{degrees}C. However, available data particularly those on creep rupture behavior, weldability and the properties of weldments are not sufficient for a comprehensive evaluation of this steel. This paper attempts to fill this gap and describes the characteristics of this new steel and its weldments.

  4. The role of nitrogen in the preferential chromium segregation on the ferritic stainless steel (1 1 1) surface

    International Nuclear Information System (INIS)

    The temperature dependence on the segregation behavior of the ferritic stainless steel single crystal (1 1 1) surface morphology has been examined by scanning tunneling microscopy (STM), Auger electron spectroscopy (AES), and low energy electron diffraction (LEED). AES clearly showed the surface segregations of chromium and nitrogen upon annealing. Nanoscale triangular chromium nitride clusters were formed around 650 deg. C and were regularly aligned in a hexagonal configuration. In contrast, for the ferritic stainless steel (1 1 1) surface with low-nitrogen content, chromium and carbon were found to segregate on the surface upon annealing and Auger spectra of carbon displayed the characteristic carbide peak. For the low-nitrogen surface, LEED identified a facetted surface with (2 x 2) superstructure at 650 deg. C. High-resolution STM identified a chromium carbide film with segregated carbon atoms randomly located on the surface. The facetted (2 x 2) superstructure changed into a (3 x 3) superstructure with no faceting upon annealing at 750 deg. C. Also, segregated sulfur seems to contribute to the reconstruction or interfacial relaxation between the ferritic stainless steel (1 1 1) substrate and chromium carbide film.

  5. Simple and direct estimation chromium in different grades of steels using UV-visible spectrophotometer and associated measurement uncertainties

    International Nuclear Information System (INIS)

    Chromium is one of the important elements that provide desirable strength to different grades of steels which are chosen as structural materials for upcoming fast breeder reactors. Therefore its estimation is an important part of qualification of steels for desired applications. Several methods have been cited in literature for the estimation of chromium in steels which include most sophisticated instruments like XRFS, spark based OES, UV-Visible spectrophotometer and also classical volumetric titration. Being surface based techniques, both XRFS and spark OES have their own limitations of using matrix matching standards apart from usage of high cost instrumentation. Similarly, volumetric method being time consuming one and also the method cited in involves cumbersome chemical treatment to convert entire chromium in to measurable form of Cr (VI) and subsequent measurement by UV-Visible Spectrophotometer at 350 nm or 373 nm. As this method involves time consuming sample preparation step, it is also not a preferred method for an industrial laboratory where high analytical loads normally exists and quick analytical feedback is an issue. In view of limitations in the method cited above, an attempt has been made to develop a simple and direct method for estimation of chromium in different grades of steels containing chromium in the range of 4.75%-26%. Further, present paper also evaluates the measurement uncertainty (MU) in measurement of chromium in different grades of steels. The developed method involves the dissolution of steel in aqua-regia followed by perchloric acid fuming to convert total chromium to Cr (VI) and subsequent measurement at 447 nm after adding phosphoric acid to the suitable aliquot taken from stock solution. Phosphoric acid is added to mask iron present in solution. For the purpose to quantify measurement uncertainty, the methodology as given in EURACHEM/CITAC guide CG-4 has been followed. The expanded uncertainty at 95% confidence limit is

  6. Study of corrosion behavior of a 22% Cr duplex stainless steel : influence of nano-sized chromium nitrides and exposure temperature

    OpenAIRE

    Bettini, Eleonora; Kivisäkk, Ulf; Leygraf, Christofer; Pan, Jinshan

    2013-01-01

    Chromium nitrides may precipitate in duplex stainless steels during processing and their influence on the corrosion behavior is of great importance for the steel performance. In this study, the influence of nano-sized quenched-in chromium nitrides on the corrosion behavior of a heat treated 2205 duplex stainless steel was investigated at room temperature and 50 °C (just above critical pitting temperature). The microstructure was characterized by SEM/EDS and AFM analyses, and quenched-in nitri...

  7. The determination of manganese uranium, chromium, copper, and molibdenum, in special steel(uranium steel) by neutron activation analysis

    International Nuclear Information System (INIS)

    Manganese, uranium, and chromium, in special steel were determined by non-destructive technique, while copper and molybdenum were determined by destructive technique. The concentration of manganese, uranium, and chromium, were determined by Ge(Li)γ spectrometry from the peak area of the radioisotopes 556Mn, 239Np, 51Cr, at energies of 846 keV, 228 keV, and 321 keV, respectively after 1 day, 2 days, and 20 days cooling. Copper was extracted from its hydrochloric acid solution at pH 2 with 0.15% dithizone solution and molybdenum was extracted from its sulfuric acid solution at pH 0.85 with 4% oxine solution. Copper was determined from the peak area of the radioisotope 64Cu at the energy of 511 keV and mlybdenum was determined from the peak area of the radioisotope 99Mo at the energy of 140 keV, by means of γ spectrometry Ge(Li). The irradiation time was 24 hours in OSIRIS reactor at thermal neutron flux of about 3.5 x 1013 n cm-2s1. (author)

  8. In situ synchrotron X-ray diffraction study of the effect of chromium additions to the steel and solution on CO2 corrosion of pipeline steels

    International Nuclear Information System (INIS)

    Highlights: •We studied the effect of chromium on CO2 corrosion processes. •Chromium addition accelerates the onset of siderite and chukanovite precipitation. •One of the key effects is to decrease the critical supersaturation for siderite nucleation. -- Abstract: We demonstrate the important effects of chromium in the steel composition and of Cr3+ ions in solution on the nucleation and growth of corrosion layers in a CO2 environment. We propose that high-valent metal cations in solution (within the boundary layer) catalyse the nucleation of siderite, which otherwise has a high critical supersaturation for precipitation. One of the key effects of small alloy additions to the steel is to put into the local solution species that decrease the critical supersaturation for siderite and modify the growth rate of the scale, thereby promoting the formation of an adherent and protective scale

  9. Corrosion resistance enhancement of SAE 1020 steel after Chromium implantation by nitrogen ion recoil

    Directory of Open Access Journals (Sweden)

    Geraldo Francisco Gomes

    2005-12-01

    Full Text Available SAE 1020 construction steel is widely used as mortar reinforcement and small machine parts, but aside good surface properties as high ductility, hardness and wear resistance, its surface is prone to severe corrosion. As it is known, Chromium in amount over 12%-13% in the Fe alloys renders them resistance to several corrosive attacks. SAE 1020 samples were recovered with Chromium film and then bombarded either by nitrogen Ion Beam (IB or Plasma Immersion Ion Implantation (PIII to recoil implant Cr atoms in the Fe matrix. Samples treated by 100 keV N+ IB showed irregular, thin Cr profile, remaining a part of the film on the surface, to about 10 nm. Samples treated by 40 kV N PIII presented Cr layer of about 18% at., ranging to around 90 nm. Cr of the film was implanted in the Fe matrix in an almost flat profile. Results of corrosion test showed good performance of the PIII treated sample. The IB treated sample showed some enhancement over the non-treated reference and the only Cr film deposited sample showed no modification on the corrosion behavior as compared to the non-treated reference sample.

  10. The Oxidation Characteristics of Modified High-Chromium Ferritic Steel for High Temperature

    International Nuclear Information System (INIS)

    The Oxidation properties of modified high chromium ferritic steels were investigated in steam and in air at 600 .deg. C, 650 .deg. C, and in thermal cyclic condition between 400 .deg. C and 600 .deg. C. In steam, the internal oxidation occurred deeply, and the formation of Cr2O3 protective scale was prevented, so the oxidation rate was 5∼20 times higher than that in air. The oxidation rate decreased with increasing Cr content and with decreasing grain size. In the zone of internal oxidation, the microhardness was higher than that in the matrix because of the formation of fine oxide particles. Finally, the existence of W-oxide and Mo-oxide was not observed by the analysis of EPMA and XRD

  11. Heat treatment to improve the toughness of 12 percent chromium steels

    International Nuclear Information System (INIS)

    Single austenitizing and double austenitizing heat treatments are shown to improve the toughness of 12 percent chromium steels. The double austenitizing heat treatment of 1 hour at 1300 K, oil quench, 1 hour at 1150 K, oil quench and temper for 8 h at 900 K, increased the room temperature toughness of some heats by up to a factor of 4, i.e., up to approximately 60 J, and was chosen as the 'optimum' heat treatment. The improvement is due to a redistribution of the carbide precipitate and the removal of coarse grain boundary carbides. Heat treatments on cylinders 225 mm OD and 75 mm ID show that this improvement can be obtained in thick sections. The improved heat treatments should now be tried on full size CANDU end fittings. (auth)

  12. Corrosion of High Chromium Ferritic/Martensitic Steels in High Temperature Water. a Literature Review

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, P.; Lapena, J.; Blazquez, F. [Ciemat, Madrid (Spain)

    2000-07-01

    Available literature concerning corrosion of high-chromium ferritic/martensitic steels in high temperature water has been reviewed. The subjects considered are general corrosion, effect of irradiation on corrosion, stress corrosion cracking (SCC) and irradiation-assisted stress corrosion cracking (IASCC). In addition some investigations about radiation induced segregation (RIS) are shown in order to know the compositional changes at grain boundaries of these alloys and their influence on corrosion properties. The data on general corrosion indicate moderate corrosion rates in high temperature water up to 350 degree centigree. Considerably larger corrosion rates were observed under neutron irradiation. The works concerning to the behaviour of these alloys to stress corrosion cracking seem to conclude that in these materials is necessary to optimize the temper temperature and to carry out the post-weld heat treatments properly in order to avoid stress corrosion cracking. (Author) 40 refs.

  13. Corrosion of High Chromium Ferritic/Martensitic Steels in High Temperature Water. a Literature Review

    International Nuclear Information System (INIS)

    Available literature concerning corrosion of high-chromium ferritic/martensitic steels in high temperature water has been reviewed. The subjects considered are general corrosion, effect of irradiation on corrosion, stress corrosion cracking (SCC) and irradiation-assisted stress corrosion cracking (IASCC). In addition some investigations about radiation induced segregation (RIS) are shown in order to know the compositional changes at grain boundaries of these alloys and their influence on corrosion properties. The data on general corrosion indicate moderate corrosion rates in high temperature water up to 350 degree centigrade. Considerably larger corrosion rates were observed under neutron irradiation. The works concerning to the behaviour of these alloys to stress corrosion cracking seem to conclude that in these materials is necessary to optimize the temper temperature and to carry out the post-weld heat treatments properly in order to avoid stress corrosion cracking. (Author) 40 refs

  14. Tensile and pack compressive tests of some sheets of aluminum alloy, 1025 carbon steel, and chromium-nickel steel

    Science.gov (United States)

    Atchison, C S; Miller, James A

    1942-01-01

    Tensile and compressive stress-strain curves, stress-deviation curves, and secant modulus-stress curves are given for longitudinal and transverse specimens of 17S-T, 24S-T, and 24S-RT aluminum-alloy sheet in thicknesses from 0.032 to 0.081 inch, 1025 carbon steel sheet in thicknesses of 0.054 and 0.120 inch, and chromium-nickel steel sheet in thicknesses form 0.020 to 0.0275 inch. Significant differences were found between the tensile and the compressive stress-strain curves, and also the corresponding corollary curves; similarly, differences were found between the curves for the longitudinal and transverse directions. These differences are of particular importance in considering the compressive strength of aircraft structures made of thin sheet. They are explored further for the case of compression by giving tangent modulus-stress curves in longitudinal and transverse compression and dimensionless curves of the ratio of tangent modulus to Young's modulus and of the ratio of reduced modulus for a rectangular section to Young's modulus, both plotted against the ratio of stress to secant yield strength.

  15. Avoiding chromium transport from stainless steel interconnects into contact layers and oxygen electrodes in intermediate temperature solid oxide electrolysis stacks

    Science.gov (United States)

    Schlupp, Meike V. F.; Kim, Ji Woo; Brevet, Aude; Rado, Cyril; Couturier, Karine; Vogt, Ulrich F.; Lefebvre-Joud, Florence; Züttel, Andreas

    2014-12-01

    We investigated the ability of (La0.8Sr0.2)(Mn0.5Co0.5)O3-δ (LSMC) and La(Ni0.6Fe0.4)O3-δ (LNF) contact coatings to avoid the transport of Cr from steel interconnects to solid oxide electrolysis electrodes, especially to the anode. The transport of chromium from commercial Crofer 22 APU (ThyssenKrupp) and K41X (AISI441, Aperam Isbergues) steels through LSMC and LNF contact coatings into adjacent (La0.8Sr0.2)MnO3-δ (LSM) oxygen electrodes was investigated in an oxygen atmosphere at 700 °C. Chromium concentrations of up to 4 atom% were detected in the contact coatings after thermal treatments for 3000 h, which also lead to the presence of chromium in adjacent LSM electrodes. Introduction of a dense (Co,Mn)3O4 coating between steel and contact coating was necessary to prevent the diffusion of chromium into contact coatings and electrodes and should lead to extended stack performance and lifetime.

  16. Corrosion behavior of a high-chromium duplex stainless steel with minor additions of ruthenium in sulfuric acid

    Energy Technology Data Exchange (ETDEWEB)

    Potgieter, J.H. [Pretoria Portland Cement, Johannesburg (South Africa). Technical Services Dept.; Brookes, H.C. [Univ. of Natal, Durban (South Africa). Dept. of Chemistry

    1995-04-01

    The influence of small ruthenium additions on the corrosion behavior of high-chromium duplex stainless steels (DSS) was studied. Ruthenium additions ({le} 0.28%) increased the corrosion resistance of the base alloy by simultaneously improving hydrogen evolution efficiency and inhibiting anodic dissolution. The corrosion behavior of the high-chromium DSS with small ruthenium additions differed somewhat from behavior of similar duplex alloys of the 22%-Cr type. The lowering of hydrogen overpotential, which promotes an elevated corrosion potential leading to passivity, was much more significant in the 29%-Cr duplex alloys than in the 22%-Cr types.

  17. Corrosion behavior of Al-Fe-sputtering-coated steel, high chromium steels, refractory metals and ceramics in high temperature Pb-Bi

    International Nuclear Information System (INIS)

    Corrosion tests of Al-Fe-coated steel, high chromium steels, refractory metals and ceramics were carried out in high temperature Pb-Bi at 700 C degrees. Oxygen concentrations in this experiment were 6.8*10-7 wt.% for Al-Fe-coated steels and 5*10-6 wt.% for high chromium steels, refractory metals and ceramics. All specimens were immersed in molten Pb-Bi in a corrosion test pot for 1.000 hours. Coating was done with using the unbalanced magnetron sputtering (UBMS) technique to protect the steel from corrosion. Sputtering targets were Al and SUS-304. Al-Fe alloy was coated on STBA26 samples. The Al-Fe alloy-coated layer could be a good protection layer on the surface of steel. The whole of the Al-Fe-coated layer still remained on the base surface of specimen. No penetration of Pb-Bi into this layer and the matrix of the specimen. For high chromium steels i.e. SUS430 and Recloy10, the oxide layer formed in the early time could not prevent the penetration of Pb-Bi into the base of the steels. Refractory metals of tungsten (W) and molybdenum (Mo) had high corrosion resistance with no penetration of Pb-Bi into their matrix. Penetration of Pb-Bi into the matrix of niobium (Nb) was observed. Ceramic materials were SiC and Ti3SiC2. The ceramic materials of SiC and Ti3SiC2 had high corrosion resistance with no penetration of Pb-Bi into their matrix. (authors)

  18. Precipitation of Chromium Nitrides in the Super Duplex Stainless Steel 2507

    Science.gov (United States)

    Pettersson, Niklas; Pettersson, Rachel F. A.; Wessman, Sten

    2015-03-01

    Precipitation of chromium nitrides during cooling from temperatures in the range 1373 K to 1523 K (1100 °C to 1250 °C) has been studied for the super duplex stainless steel 2507 (UNS S32750). Characterization with optical, scanning and transmission electron microscopy was combined to quantify the precipitation process. Primarily Cr2N nitrides were found to precipitate with a high density in the interior of ferrite grains. An increased cooling rate and/or an increased austenite spacing clearly promoted nitride formation, resulting in precipitation within a higher fraction of the ferrite grains, and lager nitride particles. Furthermore, formation of the meta-stable CrN was induced by higher cooling rates. The toughness seemed unaffected by nitrides. A slight decrease in pitting resistance was, however, noticed for quenched samples with large amounts of precipitates. The limited adverse effect on pitting resistance is attributed to the small size (~200 nm) of most nitrides. Slower cooling of duplex stainless steels to allow nitrogen partitioning is suggested in order to avoid large nitrides, and thereby produce a size distribution with a smaller detrimental effect on pitting resistance.

  19. Effect of triple ion beam irradiation on mechanical properties of high chromium austenitic stainless steel

    International Nuclear Information System (INIS)

    A high-chromium austenitic stainless steel has been developed for an advanced fuel cladding tube considering waterside corrosion and irradiation embrittlement. The candidate material was irradiated in triple ion (Ni, He, H) beam modes at 573 K up to 50 dpa to simulate irradiation damage by neutron and transmutation product. The change in hardness of the very shallow surface layer of the irradiated specimen was estimated from the slope of load/depth-depth curve which is in direct proportion to the apparent hardness of the specimen. Besides, the Swift's power low constitutive equation (σ=A(ε0 + ε)n, A: strength coefficient, ε0: equivalent strain by cold rolling, n: strain hardening exponent) of the damaged parts was derived from the indentation test combined with an inverse analysis using a finite element method (FEM). For comparison, Type304 stainless steel was investigated as well. Though both Type304SS and candidate material were also hardened by ion irradiation, the increase in apparent hardness of the candidate material was smaller than that of Type304SS. The yield stress and uniform elongation were estimated from the calculated constitutive equation by FEM inverse analysis. The irradiation hardening of the candidate material by irradiation can be expected to be lower than that of Type304SS. (author)

  20. FORMATION OF CHROMIUM COATING AND COMPARATIVE EXAMINATION ON CORROSION RESISTANCE WITH 13Cr STEEL IN CO2-SATURATED SIMULATED OILFIELD BRINE

    OpenAIRE

    JIAOJUAN ZOU; FAQIN XIE; NAIMING LIN; XIAOFEI YAO; WEI TIAN; BIN TANG

    2013-01-01

    In order to enhance the surface properties of P110 oil casing tube steel and increase its usage during operation, chromium coating was fabricated by pack cementation. Scanning electron microscope, energy dispersive spectrometry and X-ray diffraction were used to investigate the surface morphology, cross-sectional microstructure, element distribution and phase constitutions of the coating. Comparative examinations on corrosion resistance between chromium coating and 13Cr stainless steel in CO2...

  1. Effects of chromium content and sodium velocity on the compatibility of high-Cr ferritic steels in a sodium environment

    International Nuclear Information System (INIS)

    To obtain fundamental data on the compatibility of high-chromium ferritic steels in sodium, high-purity Fe-0.1C-1Mo-5, 9 or 13Cr ferritic steels were prepared by vacuum melting. Test specimens of these steels which were normalized and tempered and a reference type 316 stainless steel (316 ss) were exposed to two sodium-velocity regions for periods up to 10.8 Ms in a sodium loop system which had a direct resistance main heater and was made of SUS 316. The test temperature, the maximum temperature, of the loop system in this work was 873 K, the oxygen content of sodium was 1 - 2 ppm, and the sodium velocities were about 4.0 and 0.02 m/s. The specimens exposed to the high sodium-velocity region revealed that corrosion loss at a zero downstream position of the three kinds of ferritic steels was smaller than that of the reference 316 ss ; about one fifth for the 5 and 9 %Cr steels and one half for the 13 %Cr steel. The surface analysis showed deposition of Ni that dissolved at upstream for all the ferritic steels, deposition of Cr for the 5 %Cr steel, and selective dissolution of Cr for the 9 and 13 %Cr steels. The ferritic steels without Ni and with less amounts of Cr than the reference 316 ss would result in their smaller corrosion loss than the 316 ss. Transfer of carbon, nitrogen and oxygen was not remarkable, except the carburization of the 5 %Cr steel. The specimens of the three kinds of ferritic steels which were exposed to the low sodium-velocity region revealed much smaller corrosion loss than that in the high velocity region, deposition of both Ni and Cr, and no transfer of carbon, nitrogen and oxygen except for slight carburization of the 13 %Cr steel. (author)

  2. Effect of process parameters on surface oxides on chromium-alloyed steel powder during sintering

    International Nuclear Information System (INIS)

    The use of chromium in the PM steel industry today puts high demands on the choice and control of the atmosphere during the sintering process due to its high affinity to oxygen. Particular attention is required in order to control the surface chemistry of the powder which in turn is the key factor for the successful sintering and production of PM parts. Different atmosphere compositions, heating rates and green densities were employed while performing sintering trials on water atomized steel powder pre-alloyed with 3 wt.% Cr in order to evaluate the effect on surface chemical reactions. Fracture surfaces of sintered samples were examined using high resolution scanning electron microscopy combined with X-ray microanalysis. The investigation was complemented with thermogravimetric (TG) studies. Reaction products in particulate form containing strong-oxide forming elements such as Cr, Si and Mn were formed during sintering for all conditions. Processing in vacuum results in intensive inter-particle neck development during the heating stage and consequently in the excessive enclosure of surface oxide which is reflected in less good final mechanical properties. Enhanced oxide reduction was observed in samples processed in hydrogen-containing atmospheres independent of the actual content in the range of 3–10 vol.%. An optimum heating rate was required for balancing reduction/oxidation processes. A simple model for the enclosure and growth of oxide inclusions during the sinter-neck development is proposed. The obtained results show that significant reduction of the oxygen content can be achieved by adjusting the atmosphere purity/composition. - Highlights: ► A local atmosphere microclimate is very important for sintering of PM steels. ► High risk of surface oxide enclosure between 800 and 1000 °C. ► Coalescence and agglomeration of enclosed oxides take place during sintering. ► The effect of different process parameters on the oxide reduction is examined. ► A

  3. Thermophysical Properties of a Chromium Nickel Molybdenum Steel in the Solid and Liquid Phases

    Science.gov (United States)

    Wilthan, B.; Reschab, H.; Tanzer, R.; Schützenhöfer, W.; Pottlacher, Gernot

    2008-02-01

    Numerical simulation of vacuum arc re-melting, pressurized or protective electro-slag re-melting, and ingot casting have become quite important in the metal industry. However, a major drawback of these simulation techniques is the lack of accurate thermophysical properties for temperatures above 1,500 K. Heat capacity, heat of fusion, density, and thermal conductivity are important input parameters for the heat transfer equation. Since, direct measurements of thermal conductivity of alloys in the liquid state are almost impossible, its estimation from electrical conductivity using the Wiedemann Franz law is very useful. The afore-mentioned thermophysical properties of several steels are investigated within the context of an ongoing project. Here, we present a full set of thermophysical data for the chromium nickel molybdenum steel meeting the standard DIN 1.4435 (X2CrNiMo18-14-3); these values will be used by our partner to simulate various re-melting and solidification processes. Wire-shaped samples of the steel are resistively volume-heated, as part of a fast capacitor discharge circuit. Time-resolved measurements with sub-μs resolution of current through the specimen are performed with a Pearson probe. The voltage drop across the specimen is measured with knife-edge contacts and ohmic voltage dividers, the temperature of the sample with a pyrometer, and the volumetric expansion of the wire with a fast acting CCD camera. These measurements enable the heat of fusion, the heat capacity, and the electrical resistivity to be determined as a function of temperature in the solid and liquid phases. The thermal conductivity and thermal diffusivity are estimated via the Wiedemann Franz law.

  4. The development of carbides in the phase boundary between delta ferrite and martensite in 9-14% chromium steels

    International Nuclear Information System (INIS)

    Materials with a sufficient toughness have to be used for safety-relevant components. In martensitic 12% chromium steels delta ferrite may occur, at higher contents (>0,5%) the fracture toughness of the material may be reduced considerably. This means that the DBTT (ductile to brittle transition temperature) is shifted towards higher temperatures during impact tests. In two-phase steels consisting of delta-ferrite and martensite, this behavior of brittle fracture is found to be caused by the massive dendritic carbide surrounding the delta-ferrite. The generation of this carbide is described by means of CCT diagrams (continuous cooling transformation diagrams). Carbide formation depends on both the chromium content and the cooling velocity. (orig.)

  5. Effect of Rare Earth Element on Formation and Propagation of Thermal Fatigue Crack in Low-Chromium Semi-Steel

    Institute of Scientific and Technical Information of China (English)

    XU Tao; LI Feng; CHEN Hua; YU Cui-yan

    2005-01-01

    The formation and growth of thermal fatigue crack in low-chromium semi-steel were investigated by means of optical microscope and scanning electron microscope, and the function of RE in low-chromium semi-steel was analyzed. The results show that the thermal fatigue cracks are mainly generated at eutectic carbides, and the cracks not only grow and spread but also join each other. RE can improve the eutectic carbide′s morphology, inhibit the generation and propagation of thermal fatigue cracks, and therefore promote the activation energy for the crack′s propagation, which is especially more noticeable in case of the RE modification in combination with heat treatment. The mathematical model of the crack propagation is put forward.

  6. Problems of phase identification in high-nitrogen chromium-manganese cast steel

    Directory of Open Access Journals (Sweden)

    Z. Pirowski

    2008-03-01

    Full Text Available An atzcrnpt has been madc to offcr an intcrprctation of ihc rnicrostructurc of chromium-mangancx cast stccl aftcr adding to 1his stccla targc amount of nitrogcn as an alloying clcrncnr. Nitropcn was addcd 10 rhc cast stccl by two mcthods: rhc first mcthod consistcrl inadding a nitridcd fcrrornangancsc, the second method in rcmclting thc nitrogen-rscc alloy undcr rhc atrnosphcrc of nitrogen maintaininghigh N1 prcssurc abovc the mctal meSt (33 MPa.Somc imponant diffcrcnces in the microstructurc of rhc cxamincd cast sleet havc bccn observed. dcpcnding on how the nitrogcn wasintroduced to Ihc alloy. Whcn melting was carried out undcr thc armosphcric prcssurc adding thc nitridcd fcrroaIloys. the matrix was composedof nitridcd nustcnitc, and numerous nitrides (carboni~rides wcrc forming a wcll-dcvclopcd ncrwork along tbc grain boundaries.Mcl t ing of alloy iindcr thc high prcsairc or nirrogcn enabPcs oblaining much highcr concentrarion of this clclncnt in lncral. Thc network ofprccipilarcs along lhc grain houndwics is obscrvcd to cxist no longcr. and thc Pamellar stmcturc occupics now practically ihc cnrirc mctalvolumc. Whcn :illoys arc mcltctt in rhc air, only small fragments oh the lamellar structurc, forming thc. so ca!lcd. "Chincse script" and localclusters arc! prcscnt.At this stagc of thc rcscarch. an artcmpa has bcen mad& to identify thc phascs in chromium-~nnngn~icsc cnst stccl u s i n ~a transmissionclectron rnicroscopc. Thc conducrcd slzldics pnnly confirrncd rhc conclusions resulting from ~ h ccx nminntions cnrricd out prcvioi~slyu ndcrthc optical rnicroscopc. So far. howcvcr, no consistcna answer has bccn found to thc qucstion of what typc arc Z ~ pCrc cipi~alcsp rcscnt inthe structurc of thc cxamincrh alloy.Attcmpts at furthcr intcrprcintion of thc obtained tcsults will hc taken at the next stage of thc work with n~tcntionfo ci~sscdo n thc prccipitatcsformed during rhc proccss of wlidilicat ion of thc cxnmincd chromium-manganese cast

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

    International Nuclear Information System (INIS)

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

  8. The development of advanced creep constitutive equations for high chromium alloy steel (P91) at transition stress range

    OpenAIRE

    An, Lili

    2015-01-01

    Creep damage is a time-dependent deformation in metals under a constant stress at high temperature condition. Since the 1980s, high chromium alloy steel P91 (9%Cr-1%Mo-0.25%V) is highly demanded in high temperature industries (Saha, 2003). Continuum damage mechanism is becoming a generic life assessment tool to predict the lifetime of materials at creep condition. The consitutive equations were proposed to predict the lifetime and creep behaviours of materials. The most widely used constituti...

  9. New Trends in Hot Strip Mill Roughing Mills: Characterization of High Chromium Steel and Semi-HSS Grades

    OpenAIRE

    Lecomte-Beckers, Jacqueline; Sinnaeve, Mario; Tchuindjang, Jérôme Tchoufack

    2011-01-01

    Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) are compared. The first grade known as High Chromium Steel (HCS) is presently the most widely used alloy for such an application, while the second one known as semi-High-speed Steel (semi-HSS) is the new grade developed to improve the overall performance of the work roll in the roughing stands of the HSM. In the present paper, the new semi-HSS grade is studied starting from three chemical compositions close...

  10. Influence of delta ferrite and dendritic carbides on the impact and tensile properties of a martensitic chromium steel

    International Nuclear Information System (INIS)

    Martensitic chrome steels with a high content of chromium incline to form delta ferrite frequently accompanied by massive dendritic carbide precipitations. Both phases mostly influence the mechanical properties of this steel in countercurrent manner. The relatively soft delta ferrite causes an increase of ductility and toughness, whilst the brittle dendritic carbides decreases both. Both phases mostly decrease the strength of the steel. One or the other influence will be dominant in dependence of the quantitative relation of the two phases. This is the cause for very different statements in the literature. The dendritic carbides should be avoided using a cooling rate of more than 103 K/min after the austenitization, because this phase mostly impairs the mechanical properties of the steel. However, the delta ferrite without dendritic carbides can be tolerated mostly. (orig.)

  11. Effect of welding thermal cycle on the structure and properties of new effective alloying chromium-manganese-nickel steels

    International Nuclear Information System (INIS)

    The structure and properties of efficiently alloyed chromium-manganese-nickel steels of three experimental meltings with variable content of manganese - 2% (meltings 1 and 2) and 10% (melting 3). Steel of melting 3 was additionally alloyed with molybdenum and vanadium, and that of melting 2 - with nitrogen. The effect of different cooling rates (5, 25, 100 deg C) corresponding to electroslag, automatic flux-shielded and manual arc weldings on the structure and properties of HAZ metal of the experimental melting steels. It is shown that to decrease grain growth and intensive carbide formation, when developing technology of the steel welding attempts should be made to decrease the duration of HAZ metal maintaining at high temperature and to increase cooling rate

  12. Effect of silicon on the structure, tribological behaviour, and mechanical properties of nitrogen-containing chromium-manganese austenitic steels

    International Nuclear Information System (INIS)

    The effect of silicon in quantity of 3.5-4.5 mass. % on tribological behaviour is studied for nitrogen-bearing (0.20-0.52 mass. % of nitrogen) chromium-manganese austenitic steels (10Kh15G23S4A0.20, 10Kh16G17N3S4A0.30, 10Kh19G20NS4A0.50, 12Kh19G19NS2A0.50, 10Kh18G19A0.50, 08Kh16G8N10S4A0.18). Mechanical properties and corrosion resistance of the steels are determined. Using metallographic, x-ray diffraction and electron microscopical methods a study is made into structural transformations running in the steels considered under friction and static tension. It is shown that additional silicon alloying of nitrogen-bearing chromium-manganese austenitic steels results in an essential increase of adhesion wear resistance of the materials on retention of low friction coefficient (f=0.25-0.33). A strong silicon effect on steel tribological behaviour is related with planar slip activation and with an increase of austenite strength and heat resistance

  13. Hydrogen embrittlement characterization by disk pressure tests: Test analysis and application to high chromium martensitic steels

    International Nuclear Information System (INIS)

    The paper reports and discusses the results of an experimental and numerical activity, aimed to the characterization of the influence of hydrogen on the mechanical properties of a few high chromium martensitic steels which are candidates for fusion reactor and chemical applications. Experiments were conducted with the Disk Pressure Test technique, according to which a circular thin specimen is loaded up to rupture by a uniform pressure. As a detailed analysis of the stress/strain distributions in the specimen was not available, this kind of test being mainly used to obtain comparative information about different materials, a nonlinear numerical (Finite Element) model of the specimen was set up, by which stress and strain could be accurately evaluated as a function of the applied pressure. This model was employed both for interpreting experimental results and to achieve a more general understanding of the capabilities of the Disk Pressure Test for the characterization of hydrogen embrittlement effects. The calculated strain at failure showed the typical dependence on hydrogen content, falling to very low levels as a threshold concentration is exceeded

  14. Assessment of hexavalent chromium release in Malaysian electric arc furnace steel slag for fertilizer usage

    Science.gov (United States)

    Bankole, L. K.; Rezan, S. A.; Sharif, N. M.

    2014-03-01

    This study investigates the leaching of hexavalent chromium (Cr (VI)) from electric arc furnace steel slag as Cr (VI) is classified as human carcinogen. Batch leaching tests were performed for 16 days. The lixiviants used were alkaline, de-ionized and rain water. After 16 days, Cr (VI) was found to be highest in alkaline water (0.03 mg/L) and lowest in de-ionized water (0.01 mg/L). Besides the lixiviants used, slag stirring speed and liquid to solid ratio also affect Cr (VI) released. The experimental work was complimented with slag characterization using XRF, XRD and SEM/EDX analysis. The leaching process was also simulated via Factsage software to calculate isothermal pourbaix diagrams. The Cr (VI) released was low and below the threshold of 0.1 mg/L set for public water systems. Recycle the slag as fertilizer should be considered safe as it does not exceed the safety limit set for Cr (VI) dissolution.

  15. Assessment of hexavalent chromium release in Malaysian electric arc furnace steel slag for fertilizer usage

    International Nuclear Information System (INIS)

    This study investigates the leaching of hexavalent chromium (Cr (VI)) from electric arc furnace steel slag as Cr (VI) is classified as human carcinogen. Batch leaching tests were performed for 16 days. The lixiviants used were alkaline, de-ionized and rain water. After 16 days, Cr (VI) was found to be highest in alkaline water (0.03 mg/L) and lowest in de-ionized water (0.01 mg/L). Besides the lixiviants used, slag stirring speed and liquid to solid ratio also affect Cr (VI) released. The experimental work was complimented with slag characterization using XRF, XRD and SEM/EDX analysis. The leaching process was also simulated via Factsage software to calculate isothermal pourbaix diagrams. The Cr (VI) released was low and below the threshold of 0.1 mg/L set for public water systems. Recycle the slag as fertilizer should be considered safe as it does not exceed the safety limit set for Cr (VI) dissolution

  16. Multi-scale mechanical investigation of stainless steel and cobalt-chromium stents.

    Science.gov (United States)

    Kapnisis, Konstantinos; Constantinides, Georgios; Georgiou, Harry; Cristea, Daniel; Gabor, Camelia; Munteanu, Daniel; Brott, Brigitta; Anderson, Peter; Lemons, Jack; Anayiotos, Andreas

    2014-12-01

    In-stent restenosis (ISR) remains a significant limitation despite the considerable previous clinical and investigative emphasis on the problem. Complications arising from the interaction of stent materials with the surrounding vessel wall as well as from the mechanical forces developing after implantation, play an important role in the development of ISR. To investigate the relation between mechanical factors and stent structural integrity, and to identify any structural weakness points on the geometry of commercially available Stainless Steel and Cobalt-Chromium stents, accelerated pulsatile durability tests were carried out in a simulated physiological environment. Potential spatial variations in the mechanical properties on stent struts and their role in the observed premature failures of the stent devices during operation were also examined. Fretting wear and fatigue-induced fractures were found on stent surfaces after exposure to cyclic loading similar to that arising in vivo. Nanoindentation studies performed on various locations along the stent struts have shown that the hardness of specific stent locations significantly increases after mechanical expansion. The increase in hardness was associated with a reduction of the material's ability to dissipate energy in plastic deformations, therefore an increased vulnerability to fracture and fatigue. We conclude that the locations of fatigue fractures in stent struts are controlled not only by the geometrically-driven stress concentrations developing during cyclic loading but also by the local material mechanical changes that are imparted on various parts of the stent during the deployment process. PMID:25255419

  17. Absorption of Nickel, Chromium, and Iron by the Root Surface of Primary Molars Covered with Stainless Steel Crowns

    Directory of Open Access Journals (Sweden)

    David Keinan

    2010-01-01

    Full Text Available Objective. The purpose of this study was to analyze the absorption of metal ions released from stainless steel crowns by root surface of primary molars. Study Design. Laboratory research: The study included 34 primary molars, exfoliated or extracted during routine dental treatment. 17 molars were covered with stainless-steel crowns for more than two years and compared to 17 intact primary molars. Chemical content of the mesial or distal root surface, 1 mm apically to the crown or the cemento-enamel junction (CEJ, was analyzed. An energy dispersive X-ray spectrometer (EDS was used for chemical analysis. Results. Higher amounts of nickel, chromium, and iron (5-6 times were found in the cementum of molars covered with stainless-steel crowns compared to intact molars. The differences between groups were highly significant (<.001. Significance. Stainless-steel crowns release nickel, chromium, and iron in oral environment, and the ions are absorbed by the primary molars roots. The additional burden of allergenic metals should be reduced if possible.

  18. Formation of Chromium Coating and Comparative Examination on Corrosion Resistance with 13Cr Steel in CO2-SATURATED Simulated Oilfield Brine

    Science.gov (United States)

    Zou, Jiaojuan; Xie, Faqin; Lin, Naiming; Yao, Xiaofei; Tian, Wei; Tang, Bin

    2013-08-01

    In order to enhance the surface properties of P110 oil casing tube steel and increase its usage during operation, chromium coating was fabricated by pack cementation. Scanning electron microscope, energy dispersive spectrometry and X-ray diffraction were used to investigate the surface morphology, cross-sectional microstructure, element distribution and phase constitutions of the coating. Comparative examinations on corrosion resistance between chromium coating and 13Cr stainless steel in CO2-saturated simulated oilfield brine were carried out via electrochemical measurements. The results showed that the obtained coating was uniform and compact, mainly consisted of CrxCy and doped with minor Cr2N. Chromizing treatment made it possible to create on the working surface of P110 steel with enhanced corrosion resistance, and the chromium coating indicated lower pitting corrosion sensitivity than that of 13Cr stainless steel.

  19. Microstructural characterisation of chromium slags

    OpenAIRE

    Burja, J.; F. Tehovnik; Vode, F.; Arh, B.

    2015-01-01

    In this chromium slags that form during melting of chromium alloyed steels are examined. During melting and oxidation of these steel grades a considerable amount of chromium is lost, and gained back with slag reduction. Laboratory experiments were performed to study the mechanism of chromium oxide reduction by silicon. Slags chemistry and phase composition have a strong effect on the steelmaking process. Phase analysis revealed two types of chromium oxides, calcium chromites and chromite spin...

  20. Experimental studies on improving the performance of electrochemical machining of high carbon, high chromium die steel using jet patterns

    Directory of Open Access Journals (Sweden)

    V. Sathiyamoorthy

    2014-03-01

    Full Text Available Electrochemical machining (ECM is a non-traditional process used mainly to cut hard or difficult-to-cut metals, where the application of a more traditional process is not convenient. Stiff market competition and ever-growing demand for better, durable and reliable products has brought about a material revolution, which has greatly expanded the families of difficult-to-machine materials namely highcarbon,high-chromium die steel; stainless steel and superalloys. This investigation attempts to analyze the effect of electrolyte distribution on material removal rate (MRR and surface roughness (SR on electrochemical machining of high-carbon, high-chromium die steel using NaCl aqueous solution. Three electrolyte jet patterns namely straight jet in circular, inclined jet in circular and straight jet in spiral were used for this experimentation. The results reveal that electrolyte distribution significantly improves the performance of ECM and the straight jet in spiral pattern performs satisfactorily in obtaining better MRR and surface roughness.

  1. Effect of Chromium on Corrosion Behavior of P110 Steels in CO2-H2S Environment with High Pressure and High Temperature

    Directory of Open Access Journals (Sweden)

    Jianbo Sun

    2016-03-01

    Full Text Available The novel Cr-containing low alloy steels have exhibited good corrosion resistance in CO2 environment, mainly owing to the formation of Cr-enriched corrosion film. In order to evaluate whether it is applicable to the CO2 and H2S coexistence conditions, the corrosion behavior of low-chromium steels in CO2-H2S environment with high pressure and high temperature was investigated using weight loss measurement and surface characterization. The results showed that P110 steel suffered localized corrosion and both 3Cr-P110 and 5Cr-P110 steels exhibited general corrosion. However, the corrosion rate of 5Cr-P110 was the highest among them. The corrosion process of the steels was simultaneously governed by CO2 and H2S. The outer scales on the three steels mainly consisted of FeS1−x crystals, whereas the inner scales on Cr-containing steels comprised of amorphous FeS1−x, Cr(OH3 and FeCO3, in contrast with the amorphous FeS1−x and FeCO3 mixture film of P110 steel. The more chromium the steel contains, the more chromium compounds the corrosion products contain. The addition of chromium in steels increases the uniformity of the Cr-enriched corrosion scales, eliminates the localized corrosion, but cannot decrease the general corrosion rates. The formation of FeS1−x may interfere with Cr-enriched corrosion scales and lowering the corrosion performance of 3Cr-P110 and 5Cr-P110 steels.

  2. Relation between various chromium compounds and some other elements in fumes from manual metal arc stainless steel welding.

    OpenAIRE

    Matczak, W; Chmielnicka, J

    1993-01-01

    For the years 1987-1990 160 individual samples of manual metal arc stainless steel (MMA/SS) welding fumes from the breathing zone of welders in four industrial plants were collected. Concentrations of soluble and insoluble chromium (Cr) III and Cr VI compounds as well as of some other welding fume elements (Fe, Mn, Ni, F) were determined. Concentration of welding fumes in the breathing zone ranged from 0.2 to 23.4 mg/m3. Total Cr amounted to 0.005-0.991 mg/m3 (including 0.005-0.842 mg/m3 Cr V...

  3. Surface analytical characterization of chromium-stabilized protecting oxide layers on stainless steel referring to activity buildup

    Science.gov (United States)

    Thieme, M.; Scharnweber, D.; Drechsler, L.; Heiser, C.; Adolphi, B.; Weiss, A.

    1992-08-01

    Surface analytical methods were used to characterize both protecting oxide layers formed by hydrothermal chromate treatment (HTCT) on stabilized austenitic stainless steel and hydrothermally grown corrosion product layers (CPL) within the scope of lowering the activity buildup in the primary circuit of nuclear power plants. Morphology, thickness and chromium depth distribution of the layers proved to be considerably different from each other. According to Raman microspectrometry, there were also alterations in the chemical nature of the oxide species. Preceding electropolishing gave rise to particular properties of the respective layers. Prerequisites for an optimal corrosion behaviour of the protecting layers are discussed. Titanium-containing precipitations were oxidatively transformed by HTCT.

  4. Effects of carbon content and microstructure on corrosion rate of 13% chromium steel in wet CO2 environments; Shitsujun CO2 kankyochu deno 13%Cr ko no fushoku ni oyobosu C ryo to kinzoku soshiki no eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Hara, T.; Asahi, H. [Nippon Steel Corp., Tokyo (Japan)

    1998-11-15

    Thirteen percent chromium steel is excellent in corrosion resistance of CO2. A large quantity of 13% chromium steel is used in oil and gas fields where CO2 is produced. Usually, AISI 420 13% chromium steel to which C was added 0.2% is used for an oil field tube. Since AISI 420 steel is tempered, chromium carbide is formed and the effective chromium amount in a parent phase is decreased to deteriorate the corrosion resistance of CO2. Therefore, it is desired to decrease the carbon content as far as possible for improvement of corrosion resistance of CO2. AISI 410 13% chromium steel with a carbon content of 0.1% is difficult to form {delta}-ferrite. It has a problem in manufacturing because the hot working performance is low. In this report, on the basis of AISI 420 13% chromium steel, the effects of composition on CO2 corrosion were investigated using the steel whose carbon content was changed. Ferrite, martensite, and tempered martensite differ in a corrosion rate. The corrosion rate increases in the order of martensite, ferrite, and tempered martensite. The corrosion rate of 13% chromium steel is represented by the product of the corrosion rate of each microstructure and the fraction of it. 11 refs., 12 figs., 2 tabs.

  5. Optimized chemical composition, working and heat treatment condition for resistance to irradiation assisted stress corrosion cracking of cold worked 316 and high-chromium austenitic stainless steel

    International Nuclear Information System (INIS)

    The authors have reported that the primary water stress corrosion cracking (PWSCC) in baffle former bolts made of austenitic stainless steels for PWR after long-term operation is caused by irradiation-induced grain boundary segregation. The resistance to PWSCC of simulated austenitic stainless steels whose chemical compositions are simulated to the grain boundary chemical composition of 316 stainless steel after irradiation increased with decrease of the silicon content, increases of the chromium content, and precipitation of M23C6 carbides at the grain boundaries. In order to develop resistance to irradiation assisted stress corrosion cracking in austenitic stainless steels, optimized chemical compositions and heat treatment conditions for 316CW and high-chromium austenitic stainless steels for PWR baffle former bolts were investigated. For 316CW stainless steel, ultra-low-impurities and high-chromium content are beneficial. About 20% cold working before aging and after solution treatment has also been recommended to recover sensitization and make M23C6 carbides coherent with the matrix at the grain boundaries. Heating at 700 to 725degC for 20 to 50 h was selected as a suitable aging procedure. Cold working of 5 to 10% after aging produced the required mechanical properties. The optimized composition of the high-chromium austenitic stainless steel contents 30% chromium, 30% nickel, and ultra-low impurity levels. This composition also reduces the difference between its thermal expansion coefficient and that of 304 stainless steel for baffle plates. Aging at 700 to 725degC for longer than 40 h and cold working of 10 to 15% after aging were selected to meet mechanical property specifications. (author)

  6. Cavitation erosion resistance of two steels with the same percentage of Chromium and Nickel but different Carbon content

    International Nuclear Information System (INIS)

    Hydraulic machinery repair works necessitate new materials with improved cavitation erosion resistance and simultaneously good welding properties. The present paper is concerned with the behavior at cavitation of two steels with close contents of chromium (approximately 12%) and nickel (approximate 6%) but with different carbon content (for the first 0.1% C and the second 0.036% C). The reduced carbon content is necessary for an easy welding repair work. As a result of the different chemical content, as is shown by the Schäffler diagram, the steel containing 0.1% C has a structure formed by 60% austenite and 40% martensite while those with 0.036% C has completely martensitic structure. The laboratory tests were done in two vibratory devices one with piezoelectric crystals, respecting the ASME G32-2010 Standard and the other a magnetostrictive vibratory device with nickel tube. The evaluation of the cavitation resistance was obtained with the help of cavitation erosion characteristic curves MDE (t) and MDER (t). For analyzing the steel degradation, the eroded areas were also subjected to microscopic investigations. The results show that the steel with 0.1% C has better cavitation erosion behavior than that of the steel with 0.036% C

  7. Transformation behavior in low carbon 13% chromium-3% copper stainless steel; Tei C-13%Cr-3%Cu ko no hentai kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Hara, T.; Uemori, R.; Miyasaka, A. [Nippon Steel Corp., Tokyo (Japan)

    2000-10-01

    Martensitic transformation and {gamma} {yields} {alpha} transformation behavior were investigated in low carbon 13% chromium stainless steels containing 2% nickel or 3% copper. The main conclusions are as follows: (1) Hardness of 2% nickel added low carbon 13% chromium steel was independent of cooling rate after hot working at large reduction. Structure of the steel was martensitic even after being subjected to such large reduction of 75%. This result suggests that ferritic transformation was hard to occur under an usual cooling rate because austenite phase was sufficiently stablized by the addition of chromium and nickel. (2) Austenite to ferrite transformation occurred only for the low carbon 13% chromium 3% copper steel without nickel even at the small cooling rate, such as 0.01K/s. This result was mainly attributed to the unstabilization of austenite phase which caused by the precipitation of {epsilon}-Cu. Furthermore, austenite of the steel becomes easy to transform to ferrite due to heavy hot working. This phenomenon was seemed to be caused by the increase in the area of austenite grain boundary owing to recrystallization. Thus, it was considered that the nucleation of {epsilon}-Cu at the grain boundaries promoted ferrite formation. (author)

  8. Correlations between mechanical properties and cavitation erosion resistance for stainless steels with 12% Chromium and variable contents of Nickel

    International Nuclear Information System (INIS)

    The running time of hydraulic machineries in cavitation conditions, especially blades and runners, depend on both chemical composition and mechanical properties of the used steels. The researches of the present paper have as goal to obtain new materials with improved behavior and reduced costs. There are given cavitation erosion results upon eight cast steels with martensite as principal structural constituent. The chromium content was maintained constant at approximate 12% but the nickel content was largely modified. The change of chemical content resulted in various proportions of austenite, martensite and ferrite and also in different cavitation erosion behavior. From the eight tested steels four have greater carbon content (approximately 0.1%) and the other four less carbon content (approximate 0.036%). All steels were tested separately in two laboratory facilities: T1 with magnetostrictive nickel tube (vibration amplitude 94 μm, vibration frequency 7000 ± 3% Hz, specimen diameter 14 mm and generator power 500 W) and T2 is respecting the ASTM G32-2010 Standard (vibration amplitude 50μm, vibration frequency 20000 ± 1% Hz, specimen diameter 15.8 mm and generator power 500 W). Analyzing the results it can be seen that the cavitation erosion is correlated with the mechanical properties in the way shown in 1960 by Hammitt and Garcia but is influenced by the structural constituents

  9. Investigation of iron-chromium-niobium-titanium ferritic stainless steel for solid oxide fuel cell interconnect applications

    Science.gov (United States)

    Yang, Zhenguo; Xia, Guan-Guang; Wang, Chong-Min; Nie, Zimin; Templeton, Joshua; Stevenson, Jeffry W.; Singh, Prabhakar

    As part of an effort to develop cost-effective ferritic stainless steel-based interconnects for solid oxide fuel cell (SOFC) stacks, both bare AISI441 and AISI441 coated with (Mn,Co) 3O 4 protection layers were studied in terms of its metallurgical characteristics, oxidation behavior, and electrical performance. The addition of minor alloying elements, in particular Nb, led to formation of Laves phases both inside grains and along grain boundaries. In particular, the Laves phase which precipitated out along grain boundaries during exposure at intermediate SOFC operating temperatures was found to be rich in both Nb and Si. The capture of Si in the Laves phase minimized the Si activity in the alloy matrix and prevented formation of an insulating silica layer at the scale/metal interface, resulting in a reduction in area-specific electrical resistance (ASR). However, the relatively high oxidation rate of the steel, which leads to increasing ASR over time, and the need to prevent volatilization of chromium from the steel necessitates the application of a conductive protection layer on the steel. In particular, the application of a Mn 1.5Co 1.5O 4 spinel protection layer substantially improved the electrical performance of the 441 by reducing the oxidation rate.

  10. Study of structural transformations occuring in low carbon chromium-molybdenum ferritic steels: influence of small additions of vanadium and niobium

    International Nuclear Information System (INIS)

    This study has been carried out on several low carbon chromium-molybdenum ferritic steels: 2,25%0C to 13000C. In the case of alloys with high chromium concentration and additions of vanadium and niobium, the austenitic transformation is partial, and heat treating at higher temperatures results in increased delta transformation, a phenomenon which is accentuated by an important sensitivity to decarburization. Austenitic transformation during cooling leads to two types of CCT curves according to chromium content. Variations in chemical composition and austenitizing temperature significantly modify these diagrams, in particular those of the niobium stabilized steels. The morphology of the structures produced are very diverse, without important presence of residual austenite. The tempering behaviour in anisothermal and isothermal conditions was followed, and the temperature range limits within which precipitation reactions occur were determined in view of characterizing for each alloy the different types of precipitates formed and their influence on the mechanical resistance of the alloy after tempering

  11. The influence of chromium oxide and titanium nitride layers on vacuum properties of stainless steel H17N13M2T (SS316) surface

    International Nuclear Information System (INIS)

    The outgassing rates of stainless steel H17N13M2T (SS316) covered by chromium oxide and titanium nitride have been presented. It was shown, that the modified layers are good hydrogen diffusion barrier and possess ability of decreased sorption of water steam. (author)

  12. Comparison of high temperature wear behaviour of plasma sprayed WC–Co coated and hard chromium plated AISI 304 austenitic stainless steel

    International Nuclear Information System (INIS)

    Highlights: ► WC–12wt.%Co powders were deposited to a thickness of 300 μm on to steel substrates. ► The micro hardness of the above coatings was lower than that of chromium plating. ► Wear resistance of chromium coating was increased up to five times of AISI 304 austenitic stainless steel. ► Wear resistance of chromium coat higher than plasma coat at different temperatures. -- Abstract: The wear behaviour of plasma sprayed coating and hard chrome plating on AISI 304 austenitic stainless steel substrate is experimentally investigated in unlubricated conditions. Experiments were conducted at different temperatures (room temp, 100 °C, 200 °C and 300 °C) with 50 N load and 1 m/s sliding velocity. Wear tests were carried out by dry sliding contact of EN-24 medium carbon steel pin as counterpart on a pin-on-disc wear testing machine. In both coatings, specimens were characterised by hardness, microstructure, coating density and sliding wear resistance. Wear studies showed that the hard chromium coating exhibited improved tribological performance than that of the plasma sprayed WC–Co coating. X-ray diffraction analysis (XRD) of the coatings showed that the better wear resistance at high temperature has been attributed to the formation of a protective oxide layer at the surface during sliding. The wear mechanisms were investigated through scanning electron microscopy (SEM) and XRD. It was observed that the chromium coating provided higher hardness, good adhesion with the substrate and nearly five times the wear resistance than that obtained by uncoated AISI 304 austenitic stainless steel.

  13. A new 12% chromium steel strengthened by Z-phase precipitates

    DEFF Research Database (Denmark)

    Liu, Fang; Rashidi, Masoud; Johansson, Lennart;

    2016-01-01

    In order to increase the corrosion resistance and simultaneously maintain the creep resistance of 9-12% Cr steels at 650 degrees C, a new alloy design concept was proposed, using thermodynamically stable Z-phase (CrTaN) precipitates to strengthen the steel. A new trial Z-phase strengthened 12% Cr...... steel was produced and creep tested. The steel exhibited good long-term creep resistance. Dense nano-sized Z-phase precipitates were formed at an early stage, and coarsened slowly. They remained small after more than 10,000 h. (C) 2015 Elsevier Ltd. All rights reserved.......In order to increase the corrosion resistance and simultaneously maintain the creep resistance of 9-12% Cr steels at 650 degrees C, a new alloy design concept was proposed, using thermodynamically stable Z-phase (CrTaN) precipitates to strengthen the steel. A new trial Z-phase strengthened 12% Cr...

  14. The determination, by x-ray fluorescence analysis, of platinum, palladium, ruthenium, iron, and chromium in special steels

    International Nuclear Information System (INIS)

    This report describes the analysis of special corrosion-resistant steels for ruthenium, palladium, and platinum by X-ray-fluorescence spectrometry (XRFS) and a thin-film technique. The precision of this method varies from 1 to 7 per cent, depending upon the analyte and its concentrations. The accuracy is good and compares favourably with that of other methods. The direct determination of these elements on solid samples with the use of scattered radiation as a matrix correction is only partly successful and is not recommended. The three platinum-group elements, iron, and chromium can be determined successfully in solid samples by XRFS if an empirical interelement correction method is used. The correction factors are determined by a multiple-regression method. The precision of the determination of the platinum-group elements is about 1 per cent and that of iron and chromium about 0,2 per cent. The accuracy is in most cases better than 2 per cent for all the elements determined. The method can be implemented with the use of available computer software and a small microcomputer. The two recommended laboratory methods are given as appendices to the report

  15. Study of corrosion resistance of chromium-nickel steel in calcium - hypochlorite solution. Part 1. Steels uranus b6

    OpenAIRE

    Tošković D.; Rajković Miloš B.; Stanojević D.

    2002-01-01

    Corrosion resistance of Cr - Ni (special steels) specimen is tested by electrochemical methods, numerical method of linear polarization and polarization resistance method in calcium-hypochlorite (Ca(OCl)2) solutions. With increasing of Ca(OCl)2 concentration, pH value of the solution increases, as well as active chlorine concentration and corrosion activity of the medium. According to the quantitative method of the corrosion resistance determination it can be concluded that the steels tested ...

  16. Transformation behaviour of the high temperature martensitic steels with 8-14% chromium content

    International Nuclear Information System (INIS)

    Comprehensive development work on martensitic steels belonging to the socalled 12% Cr-steel group have been performed at the Institute for Materials Research of Forschungszentrum Karlsruhe in order to meet the various requirements in nuclear and conventional energy technology. The transformation characteristics of 29 different grades of steel and 38 heats have been determined and Continuous Cooling Transformation (CCT) diagrams have been prepared. The diagrams are described in a chronological sequence by subjects because the change in chemical composition can be correlated only partly with the transformation behavior in cases where several alloying elements are simultaneously subjected to changes. In the introduction the basic difference is shown between isothermal and CCT diagrams and the transformation behavior, respectively, by the example of the Nb-free steel 1.4922 (X20CrMoV 12 1) and the Nb-containing steel 1.4914 (X18CrMoVNb 12 1). (orig.)

  17. Investigations into radiation swelling and mechanical properties of irradiated austenitic chromium-manganese steel

    International Nuclear Information System (INIS)

    Presented are the results of investigations of material with fast-dropping radioactivity-austenitic Cr-Mn steel (04Kh12G14N4YuM), damage dose dependence of swelling and mechanical properties of steel. It is shown that 04Kh12G14N4YuM steel has high radiation swelling resistance up to a damage dose of 60 dpa at temperature ranging from 340 to 530 deg C. Mechanical properties of steel are as good as those of austenitic Cr-Ni steels up to 30 dpa and 40 deg C. Ductility does not decrease lower than 2-5 %. Dose and temperature increase leads to instability of γ-solid solution, that is confirmed by the results of TEM and X-ray examinations. 4 refs.; 6 figs.; 2 tabs

  18. Comments on "Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma"

    Science.gov (United States)

    Zaytsev, Sergey M.; Popov, Andrey M.; Zorov, Nikita B.; Labutin, Timur A.

    2016-04-01

    In the paper "Sensitive analysis of carbon, chromium and silicon in steel using picosecond laser induced low pressure helium plasma" by Syahrun Nur Abdulmadjid, Nasrullah Idris, Marincan Pardede, Eric Jobiliong, Rinda Hedwig, Zener Sukra Lie, Hery Suyanto, May On Tjia, Koo Hendrik Kurniawan and Kiichiro Kagawa [Spectrochim. Acta Part B 114 (2015) 1-6], the authors presented experimental study to demonstrate the sensitive detection of C, Cr and Si in low-alloy steels under low pressure He atmosphere. Although the use of only UV-VIS spectral range for determination of these elements seems to be a beneficial, the point that needs to be commented is the result of carbon determination with the use of C I 247.856 nm line. Thermodynamic modeling based on the NIST and R. Kurucz data for the different excitation conditions in plasma demonstrates that it is hardly possible to distinguish any carbon signal due to significantly intensive iron line Fe II 247.857 nm. Authors are kindly requested to re-consider this part of their study.

  19. The present status of development of high chromium steel for FBR

    International Nuclear Information System (INIS)

    Authors perform a series of material tests for some high Cr steels to propose the most suitable high Cr steel specification for FBR pipes. Firstly, thermal expansion and heat conductivity of several high Cr steels are measured to predict optimum Cr content for FBR structural material. Secondly, influence of heat treatment conditions on long term ductility and toughness is studied to obtain the suitable properties for FBR components. Thirdly, focusing on tungsten (W) and molybdenum (Mo) which may form Laves phase, the most optimum balance of these elements is investigated based on long-term material tests and metallurgical examination results. Considering the results of the studies, a provisional specification of high Cr steel for FBR pipes is proposed. (orig.)

  20. The influence of aging on the intergranular corrosion of 22 chromium-5 nickel duplex stainless steel

    International Nuclear Information System (INIS)

    Duplex stainless steels are widely used in severe corrosion environments because of their good corrosion performance. This paper deals with the influence of aging treatments on the intergranular corrosion (IGC) resistance of a commercial duplex stainless steel, SAF 2205. Duplex stainless steel was given aging treatments in the range 773-1173 K for time periods ranging from 6 min to 100 h. Optical microscopy and XRD was carried out on the aged stainless steels for the microstructural study. The aged samples were evaluated for the IGC susceptibility with the ASTM standard practices. Potentiodynamic cyclic polarization studies were also carried out to investigate the influence of aging treatments on the passivity breakdown. The results indicate that the sigma phase gets precipitated and is responsible for grain boundary attack. (author)

  1. ATOM PROBE MICROANALYSIS OF WELD METAL IN A SUBMERGED ARC WELDED CHROMIUM-MOLYBDENUM STEEL

    OpenAIRE

    Josefsson, B.; Kvist, A.; Andrén, H.

    1987-01-01

    A submerged arc welded 2.25Cr - 1Mo steel has been investigated using electron microscopy and atom probe field ion microscopy. The bainitic microstructure of the as-welded steel consisted of ferrite and martensite. During heat treatment at 690°C the martensite transformed to ferrite and cementite and needle-shaped (Cr,Mo)2C carbides precipitated. Together with a substantial decrease in dislocation density, this resulted in an improvement of the toughness.

  2. Aspects of microstructural evolution in chromium steels in high temperature applications

    OpenAIRE

    Gustafson, Åsa

    2000-01-01

    In this thesis 9-12 % Cr steels, used for high-temperaturecomponents in fossil-fired power plants are considered. Thecreep strength of thees steels depend on their microstructurethat consists of a matrix of tempered lath martensite withdensely distributed precipitates. The mechanical properties arestrongly influenced by precipitates present in the matrix andthe more densely distributed they are the higher is thehardening effect. These particles nucleate, grow and coarsenduring use in power pl...

  3. Analysis of steady state creep behaviour of 9-12% chromium ferritic-martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Dimmler, G.; Weinert, P.; Cerjak, H. [Graz University of Technology (Austria). Institute of Materials Science

    2004-12-15

    The present work deals with the creep behaviour of 9-12% Cr steels in the steady state (secondary) creep regime in order to enable a more detailed and exact description of the creep rupture strength on the basis of the Monkman-Grant relationship. Special attention is paid to the microstructural aspects. The steady state creep behaviour has been investigated by evaluating the creep rate and the change of stress exponent of already established grades of high temperature creep resistant steels. (author)

  4. Studies of the transition zone in steelchromium cast iron bimetallic casting

    Directory of Open Access Journals (Sweden)

    S. Tenerowicz

    2010-01-01

    Full Text Available In this work authors presented the results of transition zone studies on steel – cast iron interface in bimetallic casting. During the investigations cylindrical castings with different diameter were prepared of cast iron with steel rods placed in the center. From each bimetallic casting a microsection was prepared for microhardness tests and metalographic analysis, consisting of transition zone measurement, point and linear analysis as well as quantitative analysis.

  5. Problems of phase identification in high-nitrogen chromium-manganese cast steel

    OpenAIRE

    Z. Pirowski

    2008-01-01

    An atzcrnpt has been madc to offcr an intcrprctation of ihc rnicrostructurc of chromium-mangancx cast stccl aftcr adding to 1his stccla targc amount of nitrogcn as an alloying clcrncnr. Nitropcn was addcd 10 rhc cast stccl by two mcthods: rhc first mcthod consistcrl inadding a nitridcd fcrrornangancsc, the second method in rcmclting thc nitrogen-rscc alloy undcr rhc atrnosphcrc of nitrogen maintaininghigh N1 prcssurc abovc the mctal meSt (33 MPa).Somc imponant diffcrcnces in the microstructur...

  6. Plasma nitriding of AISI 304L and AISI 316L stainless steels: effect of time in the formation of S phase and the chromium nitrides

    International Nuclear Information System (INIS)

    Plasma nitriding can improve hardness and wear resistance of austenitic stainless steels without losses in corrosion resistance. This fact relies on a nitrided layer constituted only by S phase, without chromium nitrides precipitation. In this work, the effect of nitriding time on phases formed on nitrided layer was investigated in two austenitic stainless steels: AISI 304L e AISI 316L. The samples were nitrided at 420 deg C, using a mixture of 60 % N2 and 40% H2, during 5, 7 and 9 hours. It was noted that chromium nitrides were formed on samples of AISI 304L, nitrided for 7 e 9 hours, while all nitrided samples of AISI 316L showed only formation of S phase. The nitrided layers were characterized using optical microscope and x-ray diffraction. (author)

  7. Thermal stability of metastable austenite in rapidly solidified chromium-molybdenum-vanadium tool steel powder

    International Nuclear Information System (INIS)

    Thermal stability of metastable austenite in a Cr-Mo-V tool steel of ledeburite type was investigated by tempering rapidly solidified (RS) particles at temperatures from 100 up to 700 deg. C and by continuous heating during differential thermal analysis. A rapid increase in microhardness was observed after the tempering at temperatures over 400 deg. C. According to Moessbauer effect measurements, only non-magnetic phases were observed in the RS particles after atomization, as well as after the tempering at temperatures below 540 deg. C. Above this temperature, the metastable austenite gradually transformed into martensite during cooling from the tempering temperature. The secondary hardening peak corresponding to 1220 HV appears at 600 deg. C. This temperature is higher than the temperature of the secondary hardening peak for this steel after conventional heat treatment. The thermal stability of austenite was determined and the mechanisms of phase transformations responsible for the achievement of secondary hardness in this steel following rapid solidification are described

  8. Thermal stability of metastable austenite in rapidly solidified chromium-molybdenum-vanadium tool steel powder

    Energy Technology Data Exchange (ETDEWEB)

    Grgac, P.; Moravcik, R.; Kusy, M.; Toth, I.; Miglierini, M.; Illekova, E

    2004-07-15

    Thermal stability of metastable austenite in a Cr-Mo-V tool steel of ledeburite type was investigated by tempering rapidly solidified (RS) particles at temperatures from 100 up to 700 deg. C and by continuous heating during differential thermal analysis. A rapid increase in microhardness was observed after the tempering at temperatures over 400 deg. C. According to Moessbauer effect measurements, only non-magnetic phases were observed in the RS particles after atomization, as well as after the tempering at temperatures below 540 deg. C. Above this temperature, the metastable austenite gradually transformed into martensite during cooling from the tempering temperature. The secondary hardening peak corresponding to 1220 HV appears at 600 deg. C. This temperature is higher than the temperature of the secondary hardening peak for this steel after conventional heat treatment. The thermal stability of austenite was determined and the mechanisms of phase transformations responsible for the achievement of secondary hardness in this steel following rapid solidification are described.

  9. Mössbauer studies of medium-carbon, high-chromium martensitic steels

    Science.gov (United States)

    Peters, J. A.; Kolk, B.; Bleloch, A. L.

    1986-02-01

    57Fe Mössbauer effect spectroscopy is employed to determine the relationship between the microstructure and the mechanical properties of martensitic steels with base composition Fe-10wt%Cr-0,26wt%C. The microstructure consists predominantly of two phases: martensite and austenite. The effect of low concentrations of both Mn and Ni on the structure and the mechanical properties of these steels is studied. The results indicate that Mn and Ni additions are equally effective in increasing the fraction of retained austenite. The austenite is an important phase since it is considered to be beneficial to the toughness of steel. However, we find that the impact toughness first decreases and then increases as a function of the fraction of austenite.

  10. Comparison between a high chromium steel and a semi HSS grades used as work rolls in the roughing stands of a hot strip mill

    OpenAIRE

    Tchuindjang, Jérôme Tchoufack; Lecomte-Beckers, Jacqueline

    2010-01-01

    Two alloys grades for work rolls used in the roughing stand of Hot Strip Mill (HSM) were compared. The first grade known as High Chromium Steel (HCS) is actually the alloy widely used for such an application, while the second one known as semi-High Speed Steel (semi-HSS) is the new grade developed to improve overall properties of the work roll in the roughing stands of the HSM. In the present work, the new semi-HSS grade is studied starting from 3 chemical compositions closed one to anoth...

  11. On the nature of iron-chromium oxides in stainless steel steelmaking slags

    Science.gov (United States)

    Matteazzi, P.; Magrini, M.; Ramous, E.

    1986-02-01

    A number of slags from electric steelmaking production of AISI 420 and AISI 304 steels, were examined by Mössbauer spectroscopy. The slag samples were taken before and after oxygen blowing. The slag constitution showed the presence of a metallic part, MO mixed oxide and Fe-Cr spinel (Fe2+ Fe{x/3+} Cr2-xO4' x<1).

  12. On the nature of iron-chromium oxides in stainless steel steelmaking slags

    International Nuclear Information System (INIS)

    A number of slags from electric steelmaking production of AISI 420 and AISI 304 steels, were examined by Moessbauer spectroscopy. The slag samples were taken before and after oxygen blowing. The slag constitution showed the presence of a metallic part, MO mixed oxide and Fe-Cr spinel. (Auth.)

  13. Fracture Toughness and Strength in a New Class of Bainitic Chromium-Tungsten Steels

    Energy Technology Data Exchange (ETDEWEB)

    Mao, S. X.; Sikka, V. K.

    2006-06-01

    This project dealt with developing an understanding of the toughening and stengthening mechanisms for a new class of Fe-3Cr-W(V) steels developed at Oak Ridge National Laboratory (ORNL) in collaboration with Nooter Corporation and other industrial partners. The new steele had 50% higher tensile strength up to 650 degrees Celsius than currently used steels and the potential for not requiring any postweld heat treatment (PWHT) and for reducing equipment weight by 25%. This project was closely related to the Nooter project described in the report Development of a New Class of Fe-3Cr-W(V) Ferritic steels for Industrial Process Applications (ORNL/TM-2005/82). The project was carried out jointly by the University of Pittsburgh and ORNL. The University of Pittsburgh carried out fracture toughness measurements and microstructural analysis on base metal and welded plates prepared at ORNL. The project focused on three areas. The first dealt with detailed microstructural analysis of base compositions of 3Cr-3WV and 3Cr-3WBV(Ta) in both normalized (N) and normalized and tempered (NT) conditions. The second aspect of the prject dealt with determining tensile properties and fracture toughness values of K{subIC} at room temperature for both 3Cr-3Wv and 3Cr-3WV(Ta) compositions. The third focus of the project was to measure the fracture toughness values of the base metal and the heat-affectged zone (HAZ) of a plate of Fe-3Cr-W(Mo)V steel plate welded by the gas tungsten are (GTA) process. The HAZ toughness was measured in both the as-welded and the PWHT condition.

  14. Investigations of structural transformation within metal (austenite chromium-manganese steel) at the external surface of steam superheating tubes

    Science.gov (United States)

    Bogachev, V. A.; Pshechenkova, T. P.; Shumovskaya, M. A.

    2016-04-01

    The elemental composition of an altered layer at the external surface of a steam superheating tube of grade DI59 steel is investigated after long-term operation. It is shown that the layer is located between a scale and a matrix and depleted by silicon, manganese, copper, and chromium with the maximum oxidizer affinity, enriched by iron and nickel to 90%, and mainly composed of the α-Fe phase (ferrite) with the ferromagnetic properties. The layer formed as a result of selective oxidation and diffusion from the matrix into the metal scale with the less standard free energy of the formation of sulfides and oxides. A magnetic ferrite meter is used in the experimental investigation of the layer evolution by testing grade DI59 steel for heat resistance in air environment at temperatures of 585, 650, and 700°C for 15 × 103 h; creep at a temperature of 750°C and a stress of 60 MPa; and long-term strength at temperatures of 700 and 750°C and stresses of from 30 to 80 MPa. Specimens for tests are made of tubes under as-received conditions. The relationship between the ferrite phase content in the surface metal layer and the temperature and time of test is determined. The dependence is developed to evaluate the equivalent temperature for operation of the external surface of steam superheating tubes using data of magnetic ferritometry. It is shown that operation temperatures that are determined by the ferrite phase content and the σ phase concentration in the metal structure of steam superheating tubes with the significant operating time are close. It is proposed to use magnetic ferritometry for revelation of thermal nonuniformity and worst tubes of steam superheaters of HPP boilers.

  15. Improvement of high temperature strength and low temperature toughness of high manganese-chromium austenitic steels

    International Nuclear Information System (INIS)

    High Mn-Cr austenitic steels are still considered to be an important high temperature structural material from the point of view of fast-induced radioactivity decay (FIRD) and non-magneticity. The objective of the present study is to investigate the mechanical properties of 12% Cr-15% Mn austenitic stainless steels and to compare these properties with those of the reference materials of JPCAs and JFMS, which are being investigated for the development of fusion reactor structural materials in Japan. The effects of the alloying elements V, Ti, Ta, etc. were investigated to determine the improvement of mechanical properties. Tiny precipitates of VN and Ti(C, N) raised the high-temperature strength considerably. Content of 0.1 to 0.2% C, however, formed very coarse precipitates of M23C6 type carbide on the grain boundaries, which deteriorated low temperature toughness inducing intergranular fracture. Microstructural evolution during long-term aging was also investigated. ((orig.))

  16. Oxidation and corrosion behavior of modified-composition, low-chromium 304 stainless steel alloys

    International Nuclear Information System (INIS)

    The effects of substituting less strategic elements than Cr on the oxidation and corrosion resistance of AISI 304 stainless steel were investigated. Cyclic oxidation resistance was evaluated at 870 C. Corrosion resistance was determined by exposure of specimens to a boiling copper-rich solution of copper sulfate and sulfuric acid. Alloy substitutes for Cr included Al, Mn, Mo, Si, Ti, V, Y, and misch metal. A level of about 12% Cr was the minimum amount of Cr required for adequate oxidation and corrosion resistance in the modified composition 304 stainless steels. This represents a Cr saving of at least 33%. Two alloys containing 12% Cr and 2% Al plus 2% Mo and 12% Cr plus 2.65% Si were identified as most promising for more detailed evaluation

  17. Effect of plasma nitriding time on surface properties of hard chromium electroplated AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Kocabas, Mustafa [Yildiz Technical Univ., Istanbul (Turkey). Metallurgical and Materials Engineering Dept.; Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electrical and Electronic Engineering Dept.; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey); Uelker, Suekrue [Afyon Kocatepe Univ. (Turkey). Dept. of Mechanical Engineering

    2015-06-01

    Properties of steel can be enhanced by surface treatments such as coating. In some cases, further treatments such as nitriding can also be used in order to get even better results. In order to investigate the properties of nitride layer on hard Cr coated AISI 1010 steel, substrates were electroplated to form hard Cr coatings. Then hard Cr coatings were plasma nitrided at 700 C for 3 h, 5 h and 7 h and nitride phases on the coatings were investigated by X-ray diffraction analysis. The layer thickness and surface properties of nitride films were investigated by scanning electron microscopy. The hardness and adhesion properties of Cr-N phases were examined using nano indentation and Daimler-Benz Rockwell C adhesion tests. The highest measured hardness was 24.1 GPa and all the three samples exhibited poor adhesion.

  18. Effect of lubricant on pressure-stress parameters of hot rolling of chromium-nickel steels

    International Nuclear Information System (INIS)

    The results of the commercial investigation of water emulsions of the new process lubricants of Olon tekhnicheskii and of ET-2y emulsol in hot rolling of sheets made of 20Kh23N18 (EI 417) and 12Kh18N10T (EYa 1T) steels from 8 to 10 mm thick are presented. The experimental data indicate that the lubricants substantially lower the forward creep, contact friction coefficient, force, rolling moment and pressure of metal upon rolls. The effectiveness of the lubricants depends on the plastic properties of metal and thermal and mechanical deformation conditions. The lubricants also minimize transversal unequal thickness of hot-rolled sheets. The Olon lubricant has been introduced commercially in rolling of stainless steel

  19. Investigations and analysis on the stationary creep behaviour of 9-12% chromium ferritic martensitic steels

    Energy Technology Data Exchange (ETDEWEB)

    Dimmler, G.; Weinert, P.; Cerjak, H. [Inst. for Materials Science, Welding and Forming, Graz Univ. of Technology (Austria)

    2002-07-01

    This contribution deals with the description of the creep behaviour in the stationary creep regime in order to enable a more detailed and exact description of the creep rupture strength on basis of the Monkman-Grant relation. Special focus is given therein on microstructural aspects. In general the stationary creep behaviour has been investigated by evaluating the creep rate and the change of stress exponent of already established grades of high temperature creep resistant steels. (orig.)

  20. Microstructure stability and creep behaviour of advanced high chromium ferritic steels

    Czech Academy of Sciences Publication Activity Database

    Sklenička, Václav; Kuchařová, Květa; Kudrman, J.; Svoboda, Milan; Kloc, Luboš

    43 2005, č. 1 (2005), s. 20-33. ISSN 0023-432X R&D Projects: GA ČR(CZ) GA106/02/0608; GA AV ČR(CZ) IAA2041101; GA AV ČR(CZ) 1QS200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : 9-12%Cr steels * microstructure stability * creep behaviour * nonsteady creep loading Subject RIV: JG - Metallurgy Impact factor: 0.973, year: 2005

  1. Studies of oxide reduction and nitrogen uptake in sintering of chromium-alloyed steel powder

    OpenAIRE

    Bergman, Ola

    2008-01-01

    The powder metallurgy (PM) process route is very competitive for mass production of structural steel components with complex shape, due to efficient material utilisation, low energy consumption, and short overall production time. The most commonly used alloying elements are the processing friendly metals Cu, Ni and Mo. However, the prices for these metals are today high and volatile, which threatens to make the PM process less competitive compared to conventional metal forming processes. Cons...

  2. Chromium-manganese stainless steels with nitrogen content up to 2.10 wt%

    International Nuclear Information System (INIS)

    This paper presents the possibilities of existent in the Institute of metal science (Sofia) plants for nitrogen alloying of corrosion resistant steels type CrMnMo21 18 3 with nitrogen content up to 2.10 wt%. The method of producing is with only one melting of the charge without an additional electroslag remelting under pressure (ESRP). It is used the combination method for nitrogen alloying of the melt by solid nitrogen carrier and nitrogen gaseous blowing under high pressure up to 8 MPa. It has been obtained the compact and homogeneous ingots (10 kg of each). It is proved the possibilities for producing of industrial 0.5 and 1.8 t ingots of these grades steels with nitrogen content up to 1.20 wt percentage. All ingots of both nitrogen content levels were plastic deformed by forging and rolling. The industrial ingots were forged on radial forging machine CFM-SH 500 and laboratory ingots were deformed on laboratory rolling mill quarto in IMS. After high temperature quenching (1473-1523 K; water) the high nitrogen steels have shown a very good complex of mechanical properties: yield strength (R0.2): 750-1000 MPa, tensile strength (Rm):1250-1500 MPa, relative reduction of area (Z):60-50%, Rockwell hardness : 30-50. (orig.)

  3. Corrosion-electrochemical behavior of 13% chromium (Cr) martensitic stainless steel in hydrochloric acid (HCl) solutions

    International Nuclear Information System (INIS)

    Corrosion-electrochemical behavior of commercial API5CT grade L80 type tubing made of 13Cr martensitic stainless steel enriched with microalloying elements is studied in 6, 7.5, 9, 12 and 15% HCl solutions by electrochemical methods. The corrosion morphology was examined by means of EDAX scanning electron microscope (SEM) coupled with an ESCA analyzer. The soluble corrosion products were analyzed by atomic absorption spectroscopy and colorimetric methods. General, as well as localized, corrosion is present. The severest general corrosion with a maximum rate of 26 mm/year is obtained at 15% HCl. The localized corrosion which morphologically differs as function of HCl concentrations is revealed by SEM investigation. In all the above HCl solutions, the commercial 13% Cr martensitic stainless steel tubing shows no passive state. Above 6% HCl, the microalloying elements promote forming a discontinuous film of the corrosion products. The corrosion rate slightly decreases in 15% HCl compared to the published data on a conventional 13% Cr martensitic stainless steel tubing. This is due to both the chemical composition (silicon, manganese and vanadium) and microstructural properties. Copper seems to additionally accelerate the corrosion of the alloy

  4. Creep-damage assessment of high chromium heat resistant steels and weldments

    International Nuclear Information System (INIS)

    The microstructural changes during the creep damage process were investigated on 10Cr-1Mo-1W-VNbN steel forging and the weldment of Mod.9Cr steel-12Cr steel casting, using a scanning electron microscope equipped to take electron backscatter diffraction (EBSD) patterns, and by nano-indentation. Creep rupture and interrupted creep test samples were cut at mid-section along longitudinal direction and inverse pole figures (IPF) and Kernel average misorientation (KAM) maps were obtained from EBSD patterns. Grain size and block size were clearly identified by IPF maps and proved to be good measures of creep time fraction. Area-averaged KAM (KAMave) was shown to be effective for evaluating dislocation microstructural changes during creep and for creep damage evaluation of the forging material. Nano-indentation tests were conducted at the same position in EBSD measurement, which showed a good correlation between hardness value and the square root of KAMave. The creep damage estimation curves of KAMave were obtained as a function of creep time fraction. For the fine-grained, heat-affected zone, area fraction of creep voids and grain size measured by EBSD were good measures of creep damage, while KAMave was not such a good measure.

  5. Mechanical Properties of Laser Beam Welded Ultra-high Strength Chromium Steel with Martensitic Microstructure

    Science.gov (United States)

    Dahmen, Martin; Janzen, Vitalij; Lindner, Stefan; Wagener, Rainer

    A new class of steels is going to be introduced into sheet manufacturing. Stainless ferritic and martensitic steels open up opportunities for sheet metal fabrication including hot stamping. A strength of up to 2 GPa at a fracture strain of 15% can be attained. Welding of these materials became apparently a challenge. Energy-reduced welding methods with in-situ heat treatment are required in order to ensure the delicate and complex heat control. Laser beam welding is the joining technique of choice to supply minimum heat input to the fusion process and to apply an efficient heat control. For two application cases, production of tailored blanks in as-rolled condition and welding in assembly in hot stamped conditions, welding processes have been developed. The welding suitability is shown in metallurgical investigations of the welds. Crash tests based on the KSII concept as well as fatigue tests prove the applicability of the joining method. For the case of assembly also joining with deep drawing and manganese boron steel was taken into consideration. The strength of the joint is determined by the weaker partner but can benefit from its ductility.

  6. Ratchetting behavior of advanced 9–12% chromium ferrite steel under creep–fatigue loadings: Fracture modes and dislocation patterns

    International Nuclear Information System (INIS)

    Highlights: ► Additional fatigue damage triggers the transition from ductility to brittle fracture. ► Dislocation disintegration is the main microstructural origin of premature breakdown. ► Additional fatigue damage can be ascribed to ratchetting formed in stress change. - Abstract: In order to reveal the physical mechanisms of ratchetting process under creep–fatigue loadings, following ratchetting tests in advanced 9–12% chromium ferrite steel, a study of associated fracture modes and dislocation patterns explored by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations is presented in this paper. Two main domains were observed depending both on the peak hold time and on the stress ratio, in which the ratchetting deformation and failure mechanisms were different. These two damage domains correspond to two distinct creep–ratchetting interaction mechanisms. Particular attention was paid to the dependence of ratchetting damage behavior on the stability of dislocation substructure. In addition, an attempt is made to correlate the results of the microstructural investigations with the variations of internal stress.

  7. Fabrication of plain carbon steel/high chromium white cast iron bimetal by a liquid-solid composite casting process

    Institute of Scientific and Technical Information of China (English)

    V Javaheri; H Rastegari; M Naseri

    2015-01-01

    High-chromium white cast iron (HCWCI) is one of the most widely used engineering materials in the mining and cement indus-tries. However, in some components, such as the pulverizer plates of ash mills, the poor machinability of HCWCI creates difficulties. The bimetal casting technique is a suitable method for improving the machinability of HCWCI by joining an easily machined layer of plain car-bon steel (PCS) to its hard part. In this study, the possibility of PCS/HCWCI bimetal casting was investigated using sand casting. The inves-tigation was conducted by optical and electron microscopy and non-destructive, impact toughness, and tensile tests. The hardness and chemical composition profiles on both sides of the interface were plotted in this study. The results indicated that a conventional and low-cost casting technique could be a reliable method for producing PCS/HCWCI bimetal. The interfacial microstructure comprised two distinct lay-ers:a very fine, partially spheroidized pearlite layer and a coarse full pearlite layer. Moreover, characterization of the microstructure revealed that the interface was free of defects.

  8. An organic-reagent-free method for determination of chromium(VI) in steel alloys, sewage sludge and wastewater.

    Science.gov (United States)

    Fan, Jing; Sun, Yuping; Wang, Jianji; Fan, Maohong

    2009-04-27

    One of the active areas of green chemistry research and development is in the development of new analytical methods and techniques that reduce and eliminate the use and generation of hazardous substances. In this work, a rapid and organic-reagent-free method was developed for the determination of chromium(VI) by sequential injection analysis (SIA). The method was based on the detection of a blue unstable intermediate compound resulting from the reaction of Cr(VI) with hydrogen peroxide (H(2)O(2)) in acidic medium. H(2)O(2) and its reaction products were environmentally friendly, and chromogenic reagents and organic solvents were not used in the proposed method. Different SIA parameters have been optimized and used to obtain the analytical figures of merit. Under the optimum experimental conditions, the linear range for Cr(VI) was 0.5-100.0 microg mL(-1), and the detection limit was 0.16 microg mL(-1). The sample throughput was 80 h(-1), and the total volume of only 145 microL was consumed in each determination of Cr(VI). The method was applied for the determination of Cr(VI) in seven real samples, including alloy steel, sewage sludge and wastewater samples, and the results were compared with those obtained by atomic absorption spectrometry as well as with the certified value of Cr(VI) in standard reference material. Statistical analysis revealed that there was no significant difference at 95% confidence level. PMID:19362620

  9. Monitoring of occupational exposure in manufacturing of stainless steel constructions. Part I: Chromium, iron, manganese, molybdenum, nickel and vanadium in the workplace air of stainless steel welders

    International Nuclear Information System (INIS)

    Exposure to workplace airborne pollutants was examined in a group of 20 workers dealing mainly with welding, polishing, drilling and assembling of stainless steel constructions. Monitoring of airborne particulate matter (ARM) was performed using both personal and stationary samplers. For the personal full-shift monitoring, a SKC 224 PCRX-4 constant flow rate pump was used which was connected to a sampling head with mixed cellulose matched-weight filters having a diameter of 32 mm and a 0.8 μm pore size. The constant flow rate amounted to 2 L min-1. For the stationary sampling, the ''Gent'' stacked filter unit PM10 sampler was used, operating at a flow rate of 16 L min-1. It collects particles having an equivalent aerodynamic diameter (EAD) of less than 10,um in the separate ''coarse'' (2-10 μm EAD) and ''fine'' (< 2 μm EAD) size fractions on two sequential polycarbonate (Costar, Nuclepore) filters with a 47 mm diameter. The filters of both types were analyzed by instrumental neutron activation analysis (INAA). Of the elements determined, results for chromium, iron, manganese, molybdenum, nickel and vanadium are presented. Procedures for quality assurance of both sampling and analytical stages are described. Sampling of biological material for elemental analysis (hair, nails, urine and blood and/or serum) of exposed and control persons in contamination-free conditions was also performed. In addition, saliva samples were collected for studying immunological and genotoxicity aspects of occupational exposure. (author)

  10. Atom probe field ion microscopy investigation of boron containing martensitic 9 Pct chromium steel

    Science.gov (United States)

    Hofer, P.; Miller, M. K.; Babu, S. S.; David, S. A.; Cerjak, H.

    2000-03-01

    The chemical compositions of the ferrite matrix and various other phases in an Fe-0.17 C-9 Cr-1.55 Mo-0.27 V-0.015 N-0.01B (mass pct) steel in as-received and crept conditions were measured with atom probe field ion microscopy (APFIM). The results showed the presence of some residual boron within the ferrite matrix. Analyses showed that boron was distributed within M23C6, M6C, MX, and Laves phases. Phosphor atoms were detected at the M23C6-ferrite interface in the crept condition. The results are compared to predictions from thermodynamic calculations.

  11. Anisotropy of fracture toughness of austenitic high nitrogen chromium-manganese steel

    International Nuclear Information System (INIS)

    The anisotropy of mechanical properties, in particular of the fracture toughness measured by the J-integral method, is demonstrated for industrially manufactured high strength retaining rings made from the nitrogen alloyed steel 18Mn18Cr. The RT-orientation turns out to be the weakest with regard to the resistance of the material to stable crack growth. The fracture toughness results are compared with results from calorimetric measurements. Here, also an orientation dependence of the heat irradiation energy is observed, clearly showing the same ranking of specimen orientation as the toughness data suggest. (orig.)

  12. Influence of alloying elements and nitrogen content on deformation resistance of chromium-nickel stainless steels

    International Nuclear Information System (INIS)

    Four groups of steels with a type Kh20N15 matrix differing in the contents of nitrogen and additional alloying element (Cu, Si, V or Nb) were studied for the influence of the alloying system on deformation resistance in hot rolling. The one-pass rolling was carried out at 900, 1000, 1100 and 1200 deg C with 20, 40 and 60 % reductions. Experimental data statistical processing showed that vanadium alloying results in a sharp increase of nitrogen content influence comparable with strain hardening. The hardening effect in copper- and silicon-containing alloys almost is independent of nitrogen concentration. Niobium-containing alloys lie between two above mentioned groups

  13. Loading rate effect on phase transformations in metastable chromium-nickel-manganese austenitic steels

    International Nuclear Information System (INIS)

    Investigation results are compared for metastable austenitic stainless steels tested on bending under static and dynamic conditions. The absence of qualitative difference in kinetics of phase transformations at various loading rates is shown. The observed decrease of martensite amount under dynamic bending is explained by the action of two factors: the intensity of phase transformations decreases due to a temperature increase in a deformation zone; an area of phase transformation is narrowed down due to deformation concentration in the vicinity of the point of load application. 3 refs., 1 fig., 3 tabs

  14. Corrosion of nickel-chromium deposit on AISI 316L stainless steel in radioactive water with and without fluoride at pH 4

    International Nuclear Information System (INIS)

    The electrochemical behavior of samples was studied using potentiodynamic techniques at low scan rates, cyclic voltammetry at high scan rates and electrochemical impedance spectroscopy. The surfaces were examined and analyzed by scanning electron microscopy and X-ray microanalysis, respectively. The results from these different methods are discussed. They show that the deposit is more easily corroded than the AISI 316L stainless steel in presence or absence of fluoride. With fluoride and at the prepassive potentials, the Warburg straight line indicates that there is ionic diffusion in the nickel-chromium deposit oxide. The equivalent circuits for the nickel-chromium are proposed and indicate that the deposit can take part in localized corrosion. The use of high scan rates shows the transient kinetics of the oxide formation in presence of fluoride. With fluoride, the pitting currents are higher for nickel-chromium deposits. The SEM photographs and polarization curves show that the Ni-Cr deposit is locally corroded by fluoride, leading to the possibility of crevice formation under this and in 316L stainless steel. (orig.)

  15. Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace

    Science.gov (United States)

    Keane, Michael; Siert, Arlen; Stone, Samuel; Chen, Bean T.

    2016-01-01

    Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr6+). Elemental manganese, nickel, chromium, iron emissions per unit length of weld and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered and analyzed by inductively-coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr6+. GMAW processes used were Surface Tension Transfer™, Regulated Metal Deposition™, Cold Metal Transfer™, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr6+ ranged from 50 to 7800 μg/min, and Cr6+ generation rates per g electrode ranged from 1 to 270μg/g. Elemental Cr generation rates spanned 13 to 330μg/g. Manganese emission rates ranged from 50 to 300μg/g. Nickel emission rates ranged from 4 to140 μg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as 5 times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes

  16. Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace.

    Science.gov (United States)

    Keane, Michael; Siert, Arlen; Stone, Samuel; Chen, Bean T

    2016-01-01

    Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr(6+)). Elemental manganese, nickel, chromium, iron emissions per unit length of weld, and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered, and analyzed by inductively coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr(6+). GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr(6+) ranged from 50-7800 µg/min, and Cr(6+) generation rates per g electrode ranged from 1-270 µg/g. Elemental Cr generation rates spanned 13-330 µg/g. Manganese emission rates ranged from 50-300 µg/g. Nickel emission rates ranged from 4-140 µg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as five times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes in this

  17. Influence of PWHT on Toughness of High Chromium and Nickel Containing Martensitic Stainless Steel Weld Metals

    Science.gov (United States)

    Divya, M.; Das, Chitta Ranjan; Mahadevan, S.; Albert, S. K.; Pandian, R.; Kar, Sujoy Kumar; Bhaduri, A. K.; Jayakumar, T.

    2015-06-01

    Commonly used 12.5Cr-5Ni consumable specified for welding of martensitic stainless steels is compared with newly designed 14.5Cr-5Ni consumable in terms of their suitability for repair welding of 410 and 414 stainless steels by gas tungsten arc welding process. Changes in microstructure and austenite evolution were investigated using optical, scanning electron microscopy, X-ray diffraction techniques and Thermo-Calc studies. Microstructure of as-welded 12.5Cr-5Ni weld metal revealed only lath martensite, whereas as-welded 14.5Cr-5Ni weld metal revealed delta-ferrite, retained austenite, and lath martensite. Toughness value of as-welded 12.5Cr-5Ni weld metal is found to be significantly higher (216 J) than that of the 14.5Cr-5Ni weld metal (15 J). The welds were subjected to different PWHTs: one at 923 K (650 °C) for 1, 2, 4 hours (single-stage PWHT) and another one at 923 K (650 °C)/4 h followed by 873 K (600 °C)/2 h or 873 K (600 °C)/4 h (two-stage heat treatment). Hardness and impact toughness of the weld metals were measured for these weld metals and correlated with the microstructure. The study demonstrates the importance of avoiding formation of delta-ferrite in the weld metal.

  18. Investigation of microstructure and thermal stability of pulsed plasma processed chromium ferritic-martensitic steels

    Science.gov (United States)

    Emelyanova, O.; Dzhumaev, P.; Yakushin, V.; Polsky, V.

    2016-04-01

    This paper presents results of the microstructural evolution and thermal stability of the promising Russian ferritic-martensitic steels (EP 823, EP 900, EK 181 and ChS 139) for the nuclear and fusion application after surface modification by high temperature pulsed plasma flows (HTPPF) treatment. Investigations of microstructure, topography and elemental content changes associated with irradiation by nitrogen plasma with energy density 19-28 J/ cm2 and pulse duration 20 μs were carried out. Changes in microstructure and elemental content occurring in the modified surface layer were characterized by means of scanning electron microscopy (SEM) and X-ray microanalysis (EDS and WDS). It was shown that independently of initial microstructure and phase composition, HTPPF treatment of ferritic- martensitic steels leads to formation of ultrafine homogeneous structure in the near surface layers with typical grain size ∼100 nm. Results of microstructure investigations after annealing during 1 hour demonstrates significant thermal stability of nanostructure formed by HTPPF treatment.

  19. Corrosion resistance and electrochemical properties of welded joints of chromium-nickel steel in hydrochloric acid

    International Nuclear Information System (INIS)

    Effect of alloying elements coming into electrode materials on corrosion resistance of surfaced metal and electrochemical characteristics of welded joints of the 08Kh18N10T steel have been studied (0.08% C, 1.4% Mn; 0.6% Si; 17.5O% Cr; 10.0% Ni; 0.25% Cu; 0.64% Ti; 0.016% S; 0.028% P) in 5% solution of hydrochloric acid. Plates of 200x80x10 mm dimensions have been butt welded with different electrodes. It is shown that welded joints of 08Kh18N10T steel can be subjected to selective corrosion in solutions of hydrochloric acid. Alloying of surfaced metal with niobium (up to 1%) and vanadium (up to 2%) increases corrosion resistance, preserving selective character of joint welds failure. Alloying of surfaced metal with molybdenum (2.3%), molybdenum and vanadium (2.5% Mo and 0.52% V), molybdenum and niobium (2.4 % Mo and 0.8 % Nb) increases corrosion resistance of joint weld. Heat treatment - hardening of welded joints from 1050 deg C practically levels off values of electrode potentials of basic metal and welds, close in chemical composition, as well as additionally alloyed with niobium (0.98% Nb) and niobium and molybdenum (2.4% Mo+0.8% Nb)

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

    International Nuclear Information System (INIS)

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

  1. Diffusion characteristics of plasma nitrided hard chromium on AISI 1010 steel

    Energy Technology Data Exchange (ETDEWEB)

    Danisman, Murat [Gedik Univ., Istanbul (Turkey). Electronic Engineering Dept.; Kocabas, Mustafa; Cansever, Nurhan [Yildiz Technical Univ., Istanbul (Turkey)

    2015-06-01

    In order to investigate the different Cr-N formation characteristics of plasma nitrided hard Cr coatings, Cr was electrodeposited on AISI 1010 steel and plasma nitrided at 600, 700 and 800 C for 3 h, 5 h and 7 h, respectively. Phase analyses of resulting Cr-N phases and grain size of Cr layer before and after nitriding process were calculated by X-ray diffraction analysis. Structure of nitride layer and its thickness were analyzed using scanning electron microscopy micrographs. The micrographs indicated that samples consisted of three distinctive layers. In order to distinguish these layers, scanning electron microscopy and energy dispersive spectroscopy (EDX) analysis were used as well as elemental distribution versus depth was plotted. The Cr-N diffusion was investigated by layer thickness measurements, and diffusion coefficient as well as activation energies were calculated.

  2. Hot rolling of chromium - nickel - manganese stainless steel containing nitrogen and boron

    International Nuclear Information System (INIS)

    The strength of stainless steel of the 03Kh2ON16AG6 type increases perceptibly with an increase in the nitrogen content from 0.11 to 0.37%. At the same time, however, its ductility in the region of hot deformation temperatures (red brittleness range of 800 to 1,000 deg C) decreases. Microalloying with boron (0.002 to 0.005% by calculation) permits enhancing the hot ductility to an acceptable level without adversely affecting the working properties. The mechaniusm of boron effect is analyzed. The temperature at which ingots are heated prior to rolling to achieve the desired effect must be sufficiently low. Optimum condition for two stage heating of 6.2-ton ingots are recommeded

  3. Creep-rupture tests on chromium-containing conventional and ODS steels in oxygen-controlled Pb and air at 650 °C

    International Nuclear Information System (INIS)

    Highlights: • Generally superior creep performance of ODS steels with 12–14% Cr is indicated. • Strength of 9Cr-ODS at 650°C approaches conventional 9Cr steels at decreasing load. • ODS steels show brittle primary and ductile residual fracture. • Apparent link between secondary creep rate and fracture mode of ODS steels. • Clear impact of liquid Pb at low load, corresponding to long time-to-rupture. - Abstract: Conventional martensitic steels with 9 mass% chromium (Cr), namely T91 and P92, and ODS steels with 9, 12 and 14 mass% Cr, respectively, were subjected to creep-rupture tests in stagnant oxygen-controlled lead (Pb) at 650 °C and co = 10−6 mass% dissolved oxygen. The 9Cr conventional steels were tested in the liquid metal at static engineering stress in the range from 75 to 200 MPa. 12 and 14Cr ODS were tested at 190–400 MPa, and 9Cr ODS at 75–300 MPa. Reference tests in stagnant air were carried out in the same stress ranges. The ODS steels with 12 or 14 mass% Cr, mainly tested in oxygen containing Pb, clearly exhibit a change in the stress-dependence of secondary creep rate and appearance of fracture surface at 330–400 MPa. No such change has been observed for 9Cr ODS so far. The conventional martensitic steel P92 shows a significant drop in creep strength accompanied by reduced necking and a change from ductile to brittle fracture when tested in Pb at 75 MPa (time-to-rupture tR = 13,090 h)

  4. Creep crack growth in weld metal/base metal/fusion zone regions in chromium molybdenum steels

    Energy Technology Data Exchange (ETDEWEB)

    Norris, R.H.; Saxena, A.

    1996-11-01

    An intensive study of the elevated temperature crack growth behavior of the base metal, weld metal, and heat-affected zone regions was performed on 1{1/4} chromium (Cr)-{1/2} molybdenum (Mo) and 2{1/4} Cr-1 Mo steel weldments at 538 C. Creep tests were conducted on samples removed from the weld and base metal regions of the two alloys to determine the creep deformation properties of the two different regions, whereas constant load creep crack growth tests were performed on compact-type specimens taken from all three aforementioned regions of both alloys. After the mechanical testing of the materials, extensive characterization analyses were performed on samples removed from the test specimens, which included microhardness testing, metallurgical analysis, scanning electron microscopic analysis (SEM), Auger electron spectrography (AES), cleanliness analysis, and quantification of creep-related damage. By using the information generated in this study, a model was developed to describe the crack growth in these alloys in terms of the accumulated creep damage ahead of the advancing crack front. The creep deformation behavior of these alloys is dominated by secondary and tertiary creep. The creep crack growth behavior of the alloys showed good correlation between the crack growth rate (da/dt) and the crack tip parameter (C{sub t}) in the weld metal and heat-affected zone regions. Creep crack propagation appears to occur by continuous nucleation, growth, and coalescence of grain boundary cavities. The model proposed to describe the creep crack growth in these alloys shows good agreement with the experimental results. 81 refs.

  5. Study of the simulated HAZ of a boron alloyed creep resistant 9% chromium steel

    Energy Technology Data Exchange (ETDEWEB)

    Mayr, P.; Cerjak, H. [Graz Univ. of Technology (Austria). Inst. for Materials Science, Welding and Forming

    2006-07-01

    A basic study an the weldability of a boron alloyed advanced 9% Cr steel was performed applying the so-called 'Heat Affected Zone Simulation' technique using a Gleeble 1500 thermo-mechanical testing machine. Changes in the microstructure and in the materials properties of the HAZ were examined, before and after a postweld heat treatment (PWHT) of 730 C for 12 hours by applying light-microscopy, scanning electron microscopy (SEM), different methods of analytical transmission electron microscopy, hardness measurements and Charpy-V notched bar impact tests. The microstructures at representative points during a typical welding cycle and ensuing postweld heat treatment were studied in detail. The evolution of precipitates during a characteristic welding cycle and subsequent PWHT was observed, showing the complete dissolution of all precipitates during the weld thermal cycle and re-precipitation during the PWHT. Delta-ferrite formation was observed for welding cycles with high enough peak temperatures causing retained delta-ferrite in the material after PWHT. (orig.)

  6. Internal damage processes in low alloy chromium-molybdenum steels during high-temperature creep service

    International Nuclear Information System (INIS)

    Results are presented of investigations on structure of low alloy Cr-Mo steels exhibiting internal damage after long-term creep service. It was demonstrated that intercrystalline cavitation cracks were the dominant factor in service damage of power station boiler components operating in creep regimes. Consecutive stages in development of internal damage involving intercrystalline cavitation cracking were discussed and illustrated by means of micrographs. The results seem to indicate that nucleation of creep cavities in materials under consideration is related to gain boundary slip. Evidence confirming the shear mechanism proposed by Sklenicka and Saxl for cavity coalescence was obtained. Occurrence of intercrystalline service cracking was demonstrated. Micrographs were used to illustrate wedge service nucleation modes on triple junctions depending on the direction of slip according to Change and Grant. A classification of internal damages in relation to life exhaustion was proposed for materials under consideration. A method used in industrial practice for evaluation and qualification of creep-damaged materials was presented. (author)

  7. Sigma-phase formation in high chromium ferritic steels at 650 °C

    Energy Technology Data Exchange (ETDEWEB)

    Niewolak, L., E-mail: l.niewolak@fz-juelich.de [Forschungszentrum Jülich, IEF-2, 52428 Jülich (Germany); Garcia-Fresnillo, L.; Meier, G.H. [Department of Mechanical Engineering and Materials Science, University of Pittsburgh, Pittsburgh, PA (United States); Quadakkers, W.J. [Forschungszentrum Jülich, IEF-2, 52428 Jülich (Germany)

    2015-07-25

    Highlights: • Formation of σ-FeCr phase at 650 °C in alloys Fe–30%Cr–2%(Mn,Mo,W) was investigated. • Formation of σ-FeCr phase was accelerated by interdiffusion with Ni-coating. • Mechanism of heterogeneous nucleation of σ-FeCr at BCC/FCC interface was discussed. • Mechanisms of homogenous and heterogeneous nucleation were discussed. • Improvement of isothermal section of Fe–Cr–Ni phase diagram at 650 °C was proposed. - Abstract: A binary Fe–30 wt.%Cr alloy and corresponding ternary alloys containing manganese, molybdenum or tungsten were studied with respect to σ-phase formation at 650 °C. Although even after 3000 h exposure complete equilibration was not attained, the presence of tungsten and especially molybdenum was found to promote σ-phase formation. More extensive σ-phase formation was observed in the tungsten and especially in the molybdenum-containing alloys than in the binary and manganese-containing alloy. Apparently the bulk free energy decrease driving the nucleation of σ-phase is substantially larger when tungsten or molybdenum are present in the alloy. The presence of a nickel layer, to simulate the contact between ferritic steel interconnects and nickel mesh in a Solid Oxide Fuel Cell (SOFC) results in the formation of an austenitic zone and in accelerated formation of a σ-phase rich layer at the ferrite/austenite interface, due to interdiffusion processes. This interface acts as a highly efficient heterogeneity for the nucleation of σ-phase. The nucleation is enhanced by an increased Cr/Fe-ratio at that interface. Several possible modes for the growth of the σ layer were identified but the available experimental data were not sufficient to distinguish among these. The σ-rich layer, which appears to act as an interdiffusion barrier, is thicker in the case of the binary Fe–Cr and the Fe–Cr–Mn alloy than for the molybdenum- or tungsten-rich alloys. The results show that the stability range of σ-phase is larger

  8. Sigma-phase formation in high chromium ferritic steels at 650 °C

    International Nuclear Information System (INIS)

    Highlights: • Formation of σ-FeCr phase at 650 °C in alloys Fe–30%Cr–2%(Mn,Mo,W) was investigated. • Formation of σ-FeCr phase was accelerated by interdiffusion with Ni-coating. • Mechanism of heterogeneous nucleation of σ-FeCr at BCC/FCC interface was discussed. • Mechanisms of homogenous and heterogeneous nucleation were discussed. • Improvement of isothermal section of Fe–Cr–Ni phase diagram at 650 °C was proposed. - Abstract: A binary Fe–30 wt.%Cr alloy and corresponding ternary alloys containing manganese, molybdenum or tungsten were studied with respect to σ-phase formation at 650 °C. Although even after 3000 h exposure complete equilibration was not attained, the presence of tungsten and especially molybdenum was found to promote σ-phase formation. More extensive σ-phase formation was observed in the tungsten and especially in the molybdenum-containing alloys than in the binary and manganese-containing alloy. Apparently the bulk free energy decrease driving the nucleation of σ-phase is substantially larger when tungsten or molybdenum are present in the alloy. The presence of a nickel layer, to simulate the contact between ferritic steel interconnects and nickel mesh in a Solid Oxide Fuel Cell (SOFC) results in the formation of an austenitic zone and in accelerated formation of a σ-phase rich layer at the ferrite/austenite interface, due to interdiffusion processes. This interface acts as a highly efficient heterogeneity for the nucleation of σ-phase. The nucleation is enhanced by an increased Cr/Fe-ratio at that interface. Several possible modes for the growth of the σ layer were identified but the available experimental data were not sufficient to distinguish among these. The σ-rich layer, which appears to act as an interdiffusion barrier, is thicker in the case of the binary Fe–Cr and the Fe–Cr–Mn alloy than for the molybdenum- or tungsten-rich alloys. The results show that the stability range of σ-phase is larger

  9. Influence of chemical composition, heat treatment and structure on the properties of heat-treatable nickel-chromium-molybdenum-vanadium steels for heavy forgings, especially for low-pressure turbine and generator shafts

    International Nuclear Information System (INIS)

    The following report deals with the optimization of the chemical composition of nickel-chromium-molybdenum-vanadium steels. The influence of nickel, chromium, molybdenum, and carbon on the through hardening and tempering and the structure-specific effect of the alloying elements were investigated. Measures to suppress temper brittleness are discussed, a fracture mechanics assessment is given. Furthermore, the magnetic properties and problems of heat treatment, especially in obtaining fine grain, are discussed. Examples for possibilities and limits particularly of 26 NiCrMoV 14 5 steel are discussed. (GSCH/LH)

  10. Effect of molybdenum content on creep-rupture strength and toughness of 9 % chromium ferritic heat resisting steels containing V and Nb

    International Nuclear Information System (INIS)

    The effect of molybdenum content on creep-rupture properties and room-temperature toughness of high chromium ferritic heat resisting steels was investigated. Molybdenum content was varied from 1 to 2 wt%. In order to obtain 9Cr-Mo-V-Nb ferritic steels with both high creep-rupture strength and superior toughness, the amount of delta ferrite was controlled below 25 %, and the optimum tempering condition and mechanical properties after simulated welding have been investigated. The influence of molybdenum content on creep-rupture strength and Charpy absorbed energy was investigated with respect to the ratio of delta ferrite to tempered martensite, the precipitates, and the microstructures. Charpy absorbed energy of the 0.05C-9Cr-1Mo-0.15V-0.05Nb steel tempered at 800deg C and then heated at 600∼650deg C for 104 h was as high as 20∼30 kgf-m. By contrast, Charpy absorbed energy of 0.05C-9Cr-2Mo-0.15V-0.05Nb steel was reduced to about 4kgf-m after heating at 600∼650deg C for 104 h. It is considered that the steel of 1Mo shows superior toughness because of its low carbon content and a single phase of martensite. It was concluded that combination of superior creep-rupture strength and toughness can be obtained by optimum heat treatment for the 9Cr-1Mo-V-Nb steel containing 0.05 wt%C. (author)

  11. The roles of the micro-organisms and chromium content in the corrosion of iron-chromium steels in the presence of sulfate-reducing bacteria

    International Nuclear Information System (INIS)

    Although the ability of sulfate-reducing bacteria to enhance the corrosion of steel is now widely accepted, the actual processes involved in such phenomena are still discussed. This work is dedicated to the study of the exact roles played in corrosion processes firstly, by the presence of D. vulgaris cells and, secondly, by chemical factors such as the material composition and the accumulation of sulfide ions in the solution. The use of microbiological, electrochemical and analytical experimental techniques lead to results that show the interdependence of the bacteria and the material as well as the importance of the steel composition in the adhesion of the micro-organisms and the general corrosion rates. The bacteria cells and dissolved sulfide ions do not markedly influence the general corrosion rates. They however induce surface state modifications that can result in localized corrosion phenomena

  12. Anti corrosion layer for stainless steel in molten carbonate fuel cell - comprises phase vapour deposition of titanium nitride, aluminium nitride or chromium nitride layer then oxidising layer in molten carbonate electrolyte

    DEFF Research Database (Denmark)

    2000-01-01

    Forming an anticorrosion protective layer on a stainless steel surface used in a molten carbonate fuel cell (MCFC) - comprises the phase vapour deposition (PVD) of a layer comprising at least one of titanium nitride, aluminium nitride or chromium nitride and then forming a protective layer in situ...... by replacement of the nitride ions with oxide ions in the molten carbonate electrolyte....

  13. Influence of additional alloying with nitrogen on structure and properties of high chromium steel Kh17 after hot rolling

    International Nuclear Information System (INIS)

    A study was made into the structure and mechanical properties of steel Kh17 with 0.16% N after hot rolling under various conditions. It is shown that nitrogen alloying promotes steel transition into a two-phase state (α+γ) in heating above 850 deg C and affects mechanical properties of the steel in a hot rolled state. Impact strength is at its maximum in nitrogen containing steel kh17 if the rolling is in the temperature range of α-phase solid solution. Depending on the temperatures of hot rolling beginning and completion the distinctions in steel microstructure are investigated

  14. Nickel-chromium plasma spray coatings: A way to enhance degradation resistance of boiler tube steels in boiler environment

    Science.gov (United States)

    Sidhu, Buta Singh; Prakash, S.

    2006-03-01

    Boiler tube steels, namely low carbon steel ASTM-SA-210-Grades A1 (GrA1), 1Cr-0.5Mo steel ASTM-SA213-T-11 (T11), and 2.25Cr-1 Mo steel ASTM-SA213-T-22(T22), were used as substrate steels. Ni-22Cr-10Al-1Y powder was sprayed as a bond coat 150 μm thick before a 200 μm final coating of Ni-20Cr was applied Coatings were characterized prior to testing in the environment of a coal fire boiler. The uncoated and coated steels were inserted in the platen superheater zone of a coal fired boiler at around 755°C for 10 cycles, each 100 h. Coated steels showed lower degradation (erosion-corrosion) rate than uncoated steels showed. The lowest rate was observed in the case of Ni-20Cr coated T11 steel. Among the uncoated steels, the observed rate of degradation was the lowest for the T22 steel.

  15. Structural transformations in steels containing 12% chromium and 5 or 7% nickel. Influence of the reversed austenite on the mechanical properties

    International Nuclear Information System (INIS)

    The production of austenite by the reverse martensitic transformation has been studied. The alloys concerned by this study are two 12% chromium low carbon steels containing respectively 5 and 7% nickel. Thermal treatments have been done in the intercritical temperature range. The kinetic of the α' → γ transformation, the volumic fraction of reversed austenite and its stability after a subsequent cooling have been investigated as a function of the intercritical temperature. The purpose of such treatments is to develop an optimal mixture of tempered martensite and reversed austenite structure, which should improve the studied alloys mechanical properties and especially their high temperature properties for use in fast breeders. Creep properties are better than for classical martensitic steels (containing typically 0.1 to 0.2 weight carbon), and comparable to those of 316 type austenitic steels. This improvement of the mechanical properties seems to be tightly related to the high dislocations density observed in the reversed austenite which - besides - is dispersed as thin islands in the matrix

  16. Implantation of titanium, chromium, yttrium, molybdenum, silver, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum ion source into 440C stainless steel

    International Nuclear Information System (INIS)

    Titanium, yttrium, molybdenum, silver, chromium, hafnium, tantalum, tungsten and platinum ions generated by a metal vapor vacuum arc (MEVVA) ion source were implanted into 440C stainless steel in the dose region 1017 ions cm-2 with extraction voltages of up to 70 kV. Glow discharge spectroscopy (GDS), friction coefficient, and Vickers microhardness of the specimens were studied. Grooves made by friction tests were investigated by electron probe microanalysis (EPMA). GDS showed incorporation of carbon in the yttrium, hafnium, tantalum, tungsten and platinum implanted specimens, as well as titanium implanted samples. A large amount of oxygen was observed in the yttrium implanted specimen. The friction coefficient was measured by reciprocating sliding of an unimplanted 440C ball without lubricant at a load of 0.245 N. The friction decreased and achieved a stable state after implantation of titanium, hafnium and tantalum. The friction coefficient of the platinum implanted specimen showed a gradual decrease after several cycles of sliding at high friction coefficient. The yttrium implanted sample exhibited a decreased but slightly unstable friction coefficient. Results from EPMA showed that the implanted elements, which gave decreased friction, remained even after sliding of 200 cycles. Implantation of chromium, molybdenum, silver and tungsten did not provide a decrease in friction and the implants were gone from the wear grooves after the sliding tests. (orig.)

  17. Influence of cold work and sigma phase on the pitting corrosion behavior of 25 chromium super duplex stainless steel in 3.5% sodium chloride solution.

    Energy Technology Data Exchange (ETDEWEB)

    Elhoud, A.; Deans, W. [School of Engineering, Kings College, University of Aberdeen (United Kingdom); Ezuber, H. [College of Engineering, University of Bahrain (Bahrain)

    2010-03-15

    The effect of cold work (up to 16% strain) and sigma phase precipitation (at 850 C for 10 and 60 min) on the pitting resistance of 25 chromium super duplex stainless steel were investigated in 3.5% sodium chloride solution at 70 and 90 C. Anodic polarization scans for cold worked samples revealed immunity to pitting attack at 70 C even with 16% strain. At 90 C, the alloy still showed high pitting resistance, pitting occurring at about 600 mV (SCE) for the 16% plastic strain samples. A serious deterioration of the pitting corrosion resistance was found after heating the alloy at 850 C for 10 min resulting in a clear drop in the pitting potential at 90 C. After heating for 60 min, the material showed rapid deterioration of pitting corrosion resistance at 70 C. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Effect of a Shot Peening Pre Treatment on the Fatigue Behaviour of Hard Chromium on Electroless Nickel Interlayer Coated AISI 4340 Aeronautical Steel

    Directory of Open Access Journals (Sweden)

    Marcelino P. Nascimento

    2002-06-01

    Full Text Available Multiple layer systems of coatings are considered to have larger resistance to crack propagation in comparison to coatings with simple layer. With regard to fatigue, it is possible to improve the resistance of a component with the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to analyse the effects on rotating bending fatigue behaviour of hard chromium ¾ electroless nickel multilayer system coated AISI 4340 high strength steel submitted to shot peening pre treatment. Results indicated that the interaction between the shot peening process with the multilayer system was not satisfactory, resulting in intense delamination. Fracture surface analysis by SEM was performed toward to identify the fatigue crack origin, as well as the coating-substrate delamination process.

  19. On the nature of hardening of high nitrogen steels on the basis of iron-chromium-manganese austenite

    International Nuclear Information System (INIS)

    A study is made into the efficiency of hardening in steels Kh17AG18 and Kh17AG18F with evaluating the contribution of solid solution, precipitation or strain hardening mechanisms. It is shown, that cold deformation makes the highest contribution to the hardening of high nitrogen steels

  20. Steel dust in the New York City subway system as a source of manganese, chromium, and iron exposures for transit workers.

    Science.gov (United States)

    Chillrud, Steven N; Grass, David; Ross, James M; Coulibaly, Drissa; Slavkovich, Vesna; Epstein, David; Sax, Sonja N; Pederson, Dee; Johnson, David; Spengler, John D; Kinney, Patrick L; Simpson, H James; Brandt-Rauf, Paul

    2005-03-01

    The United States Clean Air Act Amendments of 1990 reflected increasing concern about potential effects of low-level airborne metal exposure on a wide array of illnesses. Here we summarize results demonstrating that the New York City (NYC) subway system provides an important microenvironment for metal exposures for NYC commuters and subway workers and also describe an ongoing pilot study of NYC transit workers' exposure to steel dust. Results from the TEACH (Toxic Exposure Assessment, a Columbia and Harvard) study in 1999 of 41 high-school students strongly suggest that elevated levels of iron, manganese, and chromium in personal air samples were due to exposure to steel dust in the NYC subway. Airborne concentrations of these three metals associated with fine particulate matter were observed to be more than 100 times greater in the subway environment than in home indoor or outdoor settings in NYC. While there are currently no known health effects at the airborne levels observed in the subway system, the primary aim of the ongoing pilot study is to ascertain whether the levels of these metals in the subway air affect concentrations of these metals or related metabolites in the blood or urine of exposed transit workers, who due to their job activities could plausibly have appreciably higher exposures than typical commuters. The study design involves recruitment of 40 transit workers representing a large range in expected exposures to steel dust, the collection of personal air samples of fine particulate matter, and the collection of blood and urine samples from each monitored transit worker. PMID:15738337

  1. Interfacial morphology and corrosion resistance of Fe-B cast steel containing chromium and nickel in liquid zinc

    International Nuclear Information System (INIS)

    Highlights: → Fe-B steels containing Cr and Ni exhibit the best corrosion resistance in liquid zinc. → Surface layers show gamma-Fe3Zn10, delta-FeZn10, zeta-FeZn13 and eta-Zn. → Cr and Ni can enrich at the interface during the corrosion process. → Corrosion processes include leaching, formation of compounds and spalling of borides. - Abstract: The interfacial morphology and corrosion resistance of low carbon Fe-B cast steels in zinc bath at 520 deg. C were investigated. The results show Fe-B cast steel containing high Cr and Ni exhibits the best corrosion resistance to liquid zinc. The corrosion layers are composed of Γ-Fe3Zn10, δ-FeZn10, ξ-FeZn13 and η-Zn. The corrosion behaviour of Fe-B cast steels includes the following processes: the preferential leach and dissolution of Cr and Ni, the formation of Fe-Zn compounds controlled by zinc atom diffusion, and the spalling of borides without the supporting role of α-(Fe, Cr) matrix corroded by liquid zinc.

  2. Implications of total content of silicon, aluminium, chromium and formation of thin ferrite films on low ductility at high temperature in non oriented electrical steels

    Directory of Open Access Journals (Sweden)

    Equihua-Guillén, F.

    2011-10-01

    Full Text Available This work shows evidence of the implications of total additions of silicon, aluminium and chromium on low ductility during hot rolling in non-oriented electrical steels. This paper explains the reason of ductility loss at temperatures between 950 - 1000°C in electrical steels which exhibit higher Ar3 transformation temperature than C-Mn and microalloyed steels. The empirical equations to determine Ar3 temperature do not consider silicon and aluminium elements. The results show that high content of silicon, aluminium and residual concentration of chromiun considerably increases Ar3 transformation temperature in non-oriented electrical steels. The low ductility at high temperature occurs between Ae3 and Ar3 transformation temperatures. In addition, the results of this work show evidence of thin ferrite films formed near Ar3 temperature and their implications on ductility loss at high temperature.

    Este trabajo muestra evidencia de las implicaciones de la cantidad total de silicio, aluminio y cromo sobre la baja ductilidad en aceros eléctricos durante la laminación en caliente. Este artículo explica la razón de la pérdida de ductilidad a temperaturas entre 950 y 1.000°C en aceros eléctricos. Las ecuaciones empíricas para determinar la temperatura Ar3 no consideran los elementos aluminio y silicio. Los resultados muestran que altos contenidos de silicio, aluminio y la concentración residual de cromo incrementan considerablemente la temperatura de transformación Ar3 en aceros eléctricos de grano no orientado. La baja ductilidad a elevada temperatura ocurre entre las temperaturas de transformación Ae3 y Ar3. Adicionalmente, los resultados de este trabajo muestran evidencia de películas delgadas de ferrita formadas a temperaturas cercanas a Ar3 y sus implicaciones sobre la pérdida de

  3. Study of the structure and properties of metal of the major steam lines of a CCGT-420 unit made from high-chromium X10CrMoVNb9-1 (P91) steel

    Science.gov (United States)

    Grin', E. A.; Anokhov, A. E.; Pchelintsev, A. V.; Krüger, E.-T.

    2016-07-01

    The technology of manufacture of live steam lines and hot reheat lines at FINOW Rohrsysteme GmbH are discussed. These pipelines are designed for high-performance CCGT units and are made from high-chromium martensitic steel X10CrMoVNb9-1 (P91). The principles of certification and evaluation of conformance of thermal and mechanical equipment made from new construction materials with the TRCU 032-2013 technical regulation of the Customs Union are detailed. The requirements outlined in Russian and international regulatory documents regarding the manufacture of pipes and semifinished products for pipeline systems are compared. The characteristic features of high-chromium martensitic steel, which define the requirements for its heat treatment and welding, are outlined. The methodology and the results of a comprehensive analysis of metal of pipes, fittings, and weld joints of steam lines are presented. It is demonstrated that the short-term mechanical properties of metal (P91 steel) of pipes, bends, and weld joints meet the requirements of European standards and Russian technical specifications. The experimental data on long-term strength of metal of pipes from a live steam line virtually match the corresponding reference curve from the European standard, while certain experimental points for metal of bends of this steam line and metal of pipes and bends from a hot reheat line lie below the reference curve, but they definitely stay within the qualifying (20%) interval of the scatter band. The presence of a weakened layer in the heat-affected zone of weld joints of steel P91 is established. It is shown that the properties of this zone govern the short-term and long-term strength of weld joints in general. The results of synthesis and analysis of research data support the notion that the certification testing of steam lines and other equipment made from chromium steels should necessarily involve the determination of long-term strength parameters.

  4. Preliminary results on the creep and damage behaviour of a new developed Co modified 12 % chromium ferritic-martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Dimmler, G.; Weinert, P.; Schaffemak, B.; Cerjak, H. [Technical University of Graz (Austria); Hanus, R. [VOEST Alpine Foundry Linz (Austria)

    2001-07-01

    This contribution deals with first results obtained on the creep behaviour of one in the framework COST 522 newly developed cast steel respectively test melt CB8, a ferritic-martensitic steel with Co and a raised Cr content. The material has been investigated using standard metallographical methods. For the verification of the creep behaviour continuous strain measuring creep tests were performed. To study the evolving damage, in form of nucleating and growing cavities, interrupted creep tests have been used, to generate the material states for the investigations. In order to reach the highest possible resolution for the cavities, different preparation methods for the proceeding SEM investigations have been tested. In addition hardness tests and oxidation studies were performed. (orig.)

  5. Characterization of surface hardening in a nitrated chromium steel by microwave plasma type ECR (Electron Cyclotron Resonance)

    International Nuclear Information System (INIS)

    With this work it is demonstrated the possibility of performing the nitriding process by using a CVD-ECR source, based on the results obtained after treating several samples of AISI H-12 steel. Also, the main operating parameters (time of treatment, sample temperatures and gas mixture) are determined during nitriding of this steel with the mentioned source. Samples used before nitriding were quenched and tempered at 580 Centigrade degrees. Several experiments were done by using a pure nitrogen plasma with exposure times of the samples of 20 minutes at temperatures from 450 to 550 Centigrade degrees, and by using a N2 - H2 plasma with exposure times of the samples of 20, 30 and 40 minutes at temperatures from 350 to 550 Centigrade degrees. Metallography, microhardness, EDS and Auger analysis were done to observe changes suffered for the samples after treatment. (Author)

  6. 不锈钢中铬的X射线荧光光谱分析%ANALYSIS OF CHROMIUM IN STAINLESS STEEL ALLOY BY X- RAY FLUORESCENCE SPECTROMETRY

    Institute of Scientific and Technical Information of China (English)

    刘海东; 侯丽华

    2011-01-01

    以北京钢铁研究院研制的GSB 03-2028系列不锈钢标准物质作为光谱标样,采用基本参数法校正基体效应,建立了X射线荧光光谱测定不锈钢中铬元素的方法.用该方法对标准样品进行分析,分析结果和化学法分析值相吻合,10次制样测量,测定结果的相对标准偏差约为0.14%.%X - ray fluorescence spectrometric method was developed for determination of chromium in stainless steel alloy of GSB 03 - 2028 series of standard samples from Beijing Research Institute of ferrous metal. The inter-element effect was corrected by fundamental parameter method. The results were in agreement with those from AAS and chemical method with relative standard deviation of 0.14% (n=10).

  7. Influence of process parameters on thickness and wear resistance of rare earth modified chromium coatings on P110 steel synthesized by pack cementation

    Institute of Scientific and Technical Information of China (English)

    LIN Naiming; XIE Faqin; WU Xiangqing; TIAN Wei

    2011-01-01

    The pack cementation was employed to produce rare earth modified chromium coatings on P110 steel aiming at improving its performance and increasing the usage lifetime during operation. The orthogonal array design (OAD) was applied to set experiments. Contents of NH4Cl, types of RE, contents of RE, test temperature and soaking time were the main factors, and each factor was endowed with four levels.While the range analysis and analysis of variance were used to investigate the results of OAD tests on thickness and wear resistance. The results indicated that for a promising coating with higher thickness value and excellent anti-wear property, the test temperature was the most significant process factor. The potential promising conditions for chromizing treatment were: adding 1% NH4Cl and 1% LaCl3, maintaining the test temperature at 1000 ℃ for 8 h. The results of verification showed that the coating formed under the optimal process parameter had a valid thickness of 28 μm and a reduction of 0.32 mg in wear resistance test.

  8. Estimation of changes in nickel and chromium content in nickel-titanium and stainless steel orthodontic wires used during orthodontic treatment: An analytical and scanning electron microscopic study

    Directory of Open Access Journals (Sweden)

    Vandana Kararia

    2015-01-01

    Full Text Available Introduction: The biocompatibility of orthodontic dental alloys has been investigated over the past 20 years, but the results have been inconclusive. The study compares standard 3 M Unitek nickel-titanium (NiTi and stainless steel archwires with locally available JJ orthodontics wires. Scanning electron microscope (SEM study of surface changes and complexometric titration to study compositional change was performed. Materials and Methods: Ten archwires each of group 1-3 M 0.016" NiTi, group 2-JJ 0.016" NiTi, group 3-3 M 0.019" FNx010.025" SS and group 4-JJ SS contributed a 10 mm piece of wire for analysis prior to insertion in the patient and 6 weeks post insertion. SEM images were recorded at Χ2000, Χ4000 and Χ6000 magnification. The same samples were subjected to complexiometric titration using ethylenediaminetetraacetic acid to gauge the actual change in the composition. Observations and Results: The SEM images of all the archwires showed marked changes with deep scratches and grooves and dark pitting corrosion areas post intraoral use. 3M wires showed an uniform criss-cross pattern in as received wires indicating a coating which was absent after intraoral use. There was a significant release of Nickel and Chromium from both group 3 and 4. Group 2 wires released ions significantly more than group 1 (P = 0.0. Conclusion: Extensive and stringent trials are required before certifying any product to be used in Orthodontics.

  9. Electrochemical investigation of the two-stage decomposition of oxide deposits on a high-alloy chromium nickel steel by the MOPAC decontamination process

    International Nuclear Information System (INIS)

    The dissertation explains the application of the MOPAC technique for decomposition of oxide layers deposited under PWR conditions on an austenitic, high-alloy chromium nickel steel (DIN material number 1.4550). The examinations were mainly done by impedance spectrometry. With this technique, Cr(III)-oxide is oxidized to chromate in a first step, in 'oxidation solution', and the remaining oxide deposit is then dissolved in 'decontamination solution'. The various specimens used for the examinations were pre-treated ('oxidized') in water in an autoclave at 300deg C and 160 bar, remaining there for either one, two, three, six, or eight months. Extensive pre-experiments were carried out with polished sections of the same material. Comparison of the impedance spectra of these specimens with those of specimens from the autoclave were expected to yield data allowing assignment of impedance spectra to specific transformations in the oxide layers produced in the autoclave. It was found out that the treatment in oxidation solution is the decisive step for oxide decomposition, and hence for the entire result of the decontamination process. (orig.)

  10. Redox behavior of chromium on the corrosion of austenitic stainless steel (R-SUS304ULC) in 8 M nitric acid solution

    International Nuclear Information System (INIS)

    We investigated the relationship between the corrosion of austenitic stainless steel (R-SUS304ULC) and the redox behavior of chromium in nitric acid solution under three conditions – boiling at atmospheric pressure, boiling at reduced pressure, and non-boiling – to evaluate the effects of the boiling phenomenon. In the Cr(III) oxidation rate measurement, about 20% of the Cr(III) was oxidized to Cr(VI) under atmospheric-pressure boiling at 384 K after 168 h. Under non-boiling conditions at 373 K, Cr(VI) was not observed. However, about 3% of Cr(III) oxidation was observed at 373 K with reduced-pressure boiling. Thermodynamic calculations showed that the abundance of Cr(VI) in boiling nitric acid was increased over that in non-boiling nitric acid, even at the same temperature. These results show that Cr(III) is more likely to oxidize under boiling conditions than non-boiling conditions. On the other hand, in the corrosion tests, we found that the apparent reduction rate of Cr(VI) as a result of corrosion of R-SUS304ULC was more than 10 times greater than the Cr(III) oxidation rate. Therefore, the corrosion of R-SUS304ULC appears to be dominated by the rate of Cr(VI) reduction in nitric acid solution regardless of the boiling or non-boiling conditions. (author)

  11. Effect of CO2 and pressure on the stability of steels with different amounts of chromium in saline water

    International Nuclear Information System (INIS)

    Highlights: ► Corrosion behaviour of X20Cr13, X46Cr13 and 42CrMo4 under CCS conditions. ► Long term exposure of samples (up to 1 year) in laboratory experiments. ► Kinetic, microstructural and phase analysis of the corrosion products. ► Influence of pressure is shown by different phases and lower corrosion rate. - Abstract: CO2-induced corrosion of casing and tubing steels is a relevant safety issue for compressing emission gasses into deep geological layers (CCS, Carbon Capture and Storage). The influence of CO2 and pressure of the surrounding media on steels is demonstrated in laboratory experiments providing a corrosive environment similar to a geological onshore CCS-site in the Northern German Basin (T = 60 °C, p = 1 - 100 bar, Stuttgart Aquifer, CO2-flow rate of 3 l/h, 700–8000 h exposure time). Corrosion kinetics and microstructures were characterized using specimens of heat treated 42CrMo4 (1.7225, casing) and soft annealed X46Cr13 (1.4034, tubing).

  12. The influence of chromium on the pearlite-austenite transformation kinetics of the Fe–Cr–C ternary steels

    Energy Technology Data Exchange (ETDEWEB)

    Kong, Lingnan; Liu, Yaohui, E-mail: liuyaohui2005@126.com; Liu, Jia' an; Song, Yulai; Li, Shasha; Zhang, Renhang; Li, Tuanjie; Liang, Yan

    2015-11-05

    The Fe–Cr–C ternary steels containing different contents of Cr were successfully cast and further processed in the lab. Differential scanning calorimetry (DSC), optical microscope (OM), and scanning electron microscope (SEM) were employed to investigate the transformation of the Fe–Cr–C ternary steels from pearlite to austenite. It is found that the values of Ac1 and Ac3 are raised with increase in the content of Cr. In addition, the information on the transformation kinetics was obtained from experiment results and the Johnson-Mehl-Avrami-Kolmogorov model (JMAK). The obtained austenitic transformation kinetic process has been described in three overlapping steps: site saturation nucleation, diffusion-controlled growth, and impingement correction. The pre-exponential factor for diffusion decreases firstly and then increases. The activation energy for diffusion increases with the Cr content. In addition, Cr strongly affects the effective diffusion distance, the austenite nucleation sites, and the carbon activity gradient during the austenitic transformation kinetic process. - Highlights: • The pearlite-austenite transformation kinetics is researched by DSC. • The transformation kinetics is analyzed by experiment results and the JMAK model. • The activation energy and the diffusion coefficient are discussed.

  13. Benefit of chromium in reducing the rates of flow accelerated corrosion of carbon steel outlet feeders in CANDU reactors

    International Nuclear Information System (INIS)

    In the mid 1990's, wall thinning of outlet feeders due to flow accelerated corrosion (FAC) was recognized as an active mechanism in the outlet feeders of CANDU reactors. To address wall thinning of outlet feeders in new reactor construction and refurbishment projects, AECL introduced a minimum Cr concentration in its specification for the SA-106 carbon steel feeder pipe. The effectiveness of Cr in reducing FAC was subsequently demonstrated in in-reactor and out-reactor loops at AECL's Chalk River Laboratories. More recently, wall-thinning rates have been determined from wall thickness data collected from outlet feeders, containing a specified minimum Cr concentration, installed in the Point Lepreau Generating Station in 2001. This paper presents the FAC rates determined from in-service outlet feeders and compares the rates with data from previous in-reactor and out-reactor test loops, highlighting the consistency observed in results from the three sources. (author)

  14. Effect of volume ratio of liquid to solid on the interfacial microstructure and mechanical properties of high chromium cast iron and medium carbon steel bimetal

    International Nuclear Information System (INIS)

    Highlights: → Volume ratio of liquid to solid affects significantly the interfacial microstructure. → Elemental diffusion activity is increased by increasing volume ratio. → Mechanical property is improved by increasing volume ratio. - Abstract: The high chromium cast iron and medium carbon steel bimetal was fabricated by liquid-solid casting technology. The effect of volume ratios of liquid to solid (6:1, 10:1 and 12:1) on the interfacial microstructure and mechanical properties of bimetal was investigated. The interfacial microstructure was analyzed using scanning electron microscope (SEM) and transmission electron microscope (TEM). The shear strength and microhardness in as-cast condition were studied at room temperature. The results show that the volume ratios of liquid to solid affect significantly the interfacial microstructure. When liquid-solid volume ratio was 6:1, the unbonded region was detected in interface region because the imported heat energy cannot support effectively the diffusion of element, whereas, when liquid-solid volume ratios reach 10:1 and 12:1, a sound interfacial microstructure was achieved by the diffusion of C, Cr, Mo, Cu and Mn, and metallurgical bonding without unbonded region, void and hole, etc. was detected. With the increase of liquid-solid volume ratio, the elemental diffusion activity improves, resulting in the increase of width of interface transition region. At the same distance from interface, with the increase of liquid-solid volume ratio, the microhardness is degraded in HCCI, but increased in MCS. The shear strength is also improved with the increase of liquid-solid volume ratio.

  15. Principal limiting factors on the creep resistance of 9 to 12% chromium steels for power stations with enhanced steam parameters; Haupteinflussgroessen auf die Kriechbestaendigkeit von 9- bis 12%igen Cr-Staehlen fuer Kraftwerke mit erhoehten Dampfparametern

    Energy Technology Data Exchange (ETDEWEB)

    Cerjak, H.; Hofer, P.; Schaffernak, B. [Technische Univ., Graz (Austria); Spiradek, K. [Oesterreichisches Forschungszentrum Seibersdorf (Austria); Zeiler, G. [Boehler Schmiedetechnik, Kapfenberg (Austria)

    1997-09-01

    In recent years, crucial improvements have been achieved in the creep resistance of martensitic 9 to 12% chromium steels. Derived from the material X 20 CrMoV 12 1 and by virtue of its enhanced creep strength, the steel P 91 has attained increasing importance. The tungsten-alloyed variants of this type of steel, P 92 and E 911, permit higher creep strengths to be expected. At the present time, further developments are being carried out in the field of 9 to 12% chromium steels, in which the most different analytical variants under various conditions of heat treatment are planned. Creep data are ascertained by extrapolation from shorterm values, which, as experience has shown, have to be corrected downwards on many occasions in accordance with knowledge acquired from results of creep tests. This paper introduces a method of computation which permits the stability of the microstructure to be assessed. (orig.) [Deutsch] In den letzten Jahren wurden entscheidende Verbesserungen in der Kriechbestaendigkeit martensitischer 9- bis 12%iger Cr-Staehle erreicht. Ausgehend vom Werkstoff X 20 CrMoV 12 1 hat der Stahl P 91 aufgrund seiner erhoehten Zeitstandfestigkeit zunehmende Bedeutung erlangt. Die W-legierten Varianten dieses Stahltyps, P 92 und E 911, lassen hoehere Zeitstandfestigkeiten erwarten. Zur Zeit laufen weitere Entwicklungen auf dem Gebiet der 9- bis 12%igen Cr-Staehle, wobei verschiedenste Analysenvarianten in verschiedenen Waermebehandlungszustaenden vorgeschlagen werden. Zeitstanddaten werden durch Extrapolation aus Kurzzeitwerten ermittelt, die - wie die Erfahrungen gezeigt haben - vielfach nach Bekanntwerden von Ergebnissen aus Langzeitversuchen nach unten korrigiert werden mussten. Es wird eine Rechenmethode vorgestellt, die es erlaubt, die Stabilitaet der Mikrostruktur abzuschaetzen. (orig.)

  16. Abatement of Chromium Emissions from Steelmaking Slags - Cr Stabilization by Phase Separation

    OpenAIRE

    Albertsson, Galina

    2013-01-01

    Chromium is an important alloying element in stainless steel but also environmentally harmful element. A number of mineralogical phases present in the slag matrix can contain chromium and lead to chromium leaching. Chromium in slag if not stabilized, could oxidize to the cancerogenic hexavalent state, and leach out if exposed to acidic and oxygen rich environment. Other environmental concerns are slag dusting and chromium escape to the atmosphere. Despite the fact that there is a certain risk...

  17. Electrolytic dissolving ferritic stainless steel by layers and determination of chromium and silicon in the surface and the matrix of the stainless steel%电解法逐层溶解铁素体不锈钢并测定表层和基体中铬和硅的含量

    Institute of Scientific and Technical Information of China (English)

    张进; 杨建男

    2001-01-01

    以待分析的铁素体不锈钢和碳棒分别作为阳极和阴极,用由阴离子交换膜隔开的三室电解池作为采样器,对该钢样进行逐层溶解,并用氧化还原滴定法测定每一层中铬的含量。经测定,厚度约为0.03mm的表层中铬的平均含量为7.82%,基体中铬的含量为17.20%,另该表层中硅的含量为1.69%,基体中硅的含量为0.0774%,即该不锈钢表层为贫铬富硅层。%The ferritic stainless steel to be analyzed and carbon rods were used as anode and cathode, respectively. The dissolver was a triple-chamber electrolyser with the membrane placed between the chambers. The stainless steel sample was dissolved by layers, and chromium content of each layer was determined by the redox titration. The average chromium content of the surface layer about 0.03 mm thick is 7.82%, and that of the matrix of the steel is 17.20%. Silicon contents of the surface layer and the matrix are 1.69% and 0.0774%, respectively. That is to say, the surface of the ferritic stainless steel is a lager of poor chromium and rich silicon.

  18. Steel

    International Nuclear Information System (INIS)

    Composition of age hardening steel, % : Fe - (12.0-12.4) Cr - (2-2.7) Ni (0.5-0.6) Ti - (1.0-1.2) Mn - (0.03 - 0.04) C having high values of magnetoelastic internal friction and mechanical properties as well as an ability to operate under the conditions of alternating loadings are proposed. Damping properties of the steel permit to improve labour conditions. Data for the above steel on internal friction, impact strength and tensile properties are given

  19. Long-term strength and allowable stresses of grade 10Kh9MFB and X10CrMoVNb9-1 (T91/P91) chromium heat-resistant steels

    Science.gov (United States)

    Skorobogatykh, V. N.; Danyushevskiy, I. A.; Schenkova, I. A.; Prudnikov, D. A.

    2015-04-01

    Currently, grade X10CrMoVNb9-1 (T91, P91) and 10Kh9MFB (10Kh9MFB-Sh) chromium steels are widely applied in equipment manufacturing for thermal power plants in Russia and abroad. Compilation and comparison of tensile, impact, and long-term strength tests results accumulated for many years of investigations of foreign grade X10CrMoVNb9-1, T91, P91, and domestic grade 10Kh9MFB (10Kh9MFB-Sh) steels is carried out. The property identity of metals investigated is established. High strength and plastic properties of steels, from which pipes and other products are made, for operation under creep conditions are confirmed. Design characteristics of long-term strength on the basis of tests with more than one million of hour-samples are determined ( and at temperatures of 500-650°C). The table of recommended allowable stresses for grade 10Kh9MFB, 10Kh9MFB-SH, X10CrMoVNb9-1, T91, and P91 steels is developed. The long-time properties of pipe welded joints of grade 10Kh9MFB+10Kh9MFB, 10Kh9MFB-Sh+10Kh9MFB-Sh, X10CrMoVNb9-1+X10CrMoVNb9-1, P91+P91, T91+T91, 10Kh9MFB (10Kh9MFB-Sh)+X10CrMoVNb9-1(T/P91) steels is researched. The welded joint reduction factor is experimentally determined.

  20. The compatibility of chromium-aluminium steels with high pressure carbon dioxid at intermediate- temperatures; Compatibilite des aciers au chrome-aluminium avec le gaz carbonique sous pression aux temperatures moyennes

    Energy Technology Data Exchange (ETDEWEB)

    Leclercq, D.; Loriers, H.; David, R.; Darras, E. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    With a view to their use in the exchangers of nuclear reactors of the graphite-gas or heavy water-gas types, the behaviour of chromium-aluminium steels containing up to 7 per cent chromium and 1.5 per cent aluminium has been studied in the presence of high-pressure carbon dioxide at temperatures of between 400 and 700 deg. C. The two most interesting grades of steel (2 per cent Cr - 0.35 per cent Al - 0.35 per cent Mo and 7 per cent Cr - 1.5 per cent Al - 0.6 per cent Si) are still compatible with carbon dioxide up to 550 and 600 deg. C respectively. A hot dip aluminised coating considerably increases resistance to oxidation of the first grade and should make possible its use up to temperatures of at least 600 deg. C. (authors) [French] Dans l'optique de leur emploi dans les echangeurs de reacteurs nucleaires des filieres graphite-gaz ou eau lourde-gaz, le comportement en presence de gaz carbonique sous pression d'aciers au chrome-aluminium, contenant jusqu'a 7 pour cent de chrome et 1,5 pour cent d'aluminium a ete etudie entre 400 et 700 deg. C. Les deux nuances les plus interessantes (2 pour cent Cr - 0,35 pour cent Al - 0,35 pour cent Mo et 7 pour cent Cr - 1,5 pour cent Al - 0,6 pour cent Si) restent compatibles avec le gaz carbonique jusqu'a 550 et 600 deg. C respectivement. Un revetement d'aluminium, effectue par immersion dans un bain fondu, ameliore notablement la resistance a l'oxydation de la premiere et doit permettre son empioi jusqu'a 600 deg. C au moins. (auteurs)

  1. Effect of a Shot Peening Pre Treatment on the Fatigue Behaviour of Hard Chromium on Electroless Nickel Interlayer Coated AISI 4340 Aeronautical Steel

    OpenAIRE

    Marcelino P. Nascimento; Marcelo A.S. Torres; Renato C. Souza; Herman J.C. Voorwald

    2002-01-01

    Multiple layer systems of coatings are considered to have larger resistance to crack propagation in comparison to coatings with simple layer. With regard to fatigue, it is possible to improve the resistance of a component with the application of shot peening treatment, whose compressive residual stresses delay or eliminate the initiation and propagation of fatigue cracks. The aim of this study is to analyse the effects on rotating bending fatigue behaviour of hard chromium fraction three-quar...

  2. Influence of nitrogen on the corrosion behaviour of solution treated and annealed austenitic 18/10 chromium-nickel and 18/12 chromium-nickel-molybdenum steels. Pt. 1

    International Nuclear Information System (INIS)

    Investigations into the corrosion behaviour of CrNi steels with (weight-%) 0.019-0.029 C, 18.5 Cr, 11 Ni, 0.022-0.138 N and 0.020 to 0.031 C, 17.2 Cr, 13 Ni, 2.6 Mo, 0.028 to 0.130 N by the Strauss-Test, the Strauss-Test under rigid condition and the Huey-Test. The first part of this paper is devoted in particular to the analysis of structural constituents and in particular to precipitations. In the molybdenum-free steel heat treatment results in precipitation of M23C6 and Cr2N, the precipitation of the first being independent from nitrogen content. In the case of the molybdenum-bearing steels the precipitation of M23C6 is independent from nitrogen content too but is shifted toward higher temperatures. The precipitation of Cr2N is slowed down by Mo. The precipitation of other phases (chi-, sigma- and Z-phases) is affected differently by nitrogen. (orig.)

  3. Electrodeposition of black chromium thin films from trivalent chromium-ionic liquid solution

    OpenAIRE

    Eugénio, S.; Vilar, Rui; C. M. Rangel; Baskaran, I.

    2009-01-01

    In the present study, black chromium thin films were electrodeposited from a solution of 1-butyl-3- methylimidazolium tetrafluoroborate ([BMIm][BF4] ionic liquid containing trivalent chromium (Cr(III)). Homogeneous and well adherent coatings have been obtained on nickel, copper and stainless steel substrates. The nucleation and growth of the films were investigated by cyclic voltammetry and current-density/time transient techniques. SEM/EDS, XPS and XRD were used to study the morphology, chem...

  4. Comparative Tensile Flow and Work-Hardening Behavior of 9 Pct Chromium Ferritic-Martensitic Steels in the Framework of the Estrin-Mecking Internal-Variable Approach

    Science.gov (United States)

    Choudhary, B. K.; Christopher, J.

    2016-06-01

    The comparative tensile flow and work-hardening behavior of P9 steel in two different product forms, normalized and tempered plate and thick section tube plate forging, and P91 steel were investigated in the framework of the dislocation dynamics based Estrin-Mecking (E-M) one-internal-variable approach. The analysis indicated that the flow behavior of P9 and P91 steels was adequately described by the E-M approach in a wide range of temperatures. It was suggested that dislocation dense martensite lath/cell boundaries and precipitates together act as effective barriers to dislocation motion in P9 and P91 steels. At room and intermediate temperatures, the evolution of the internal-state variable, i.e., the dislocation density with plastic strain, exhibited insignificant variations with respect to temperature. At high temperatures, a rapid evolution of dislocation density with plastic strain toward saturation with increasing temperature was observed. The softer P9 steel tube plate forging exhibited higher work hardening in terms of larger gains in the dislocation density and flow stress contribution from dislocations than the P9 steel plate and P91 steel at temperatures ranging from 300 K to 873 K (27 °C to 600 °C). The evaluation of activation energy suggests that the deformation is controlled by cross-slip of dislocations at room and intermediate temperatures, and climb of dislocations at high temperatures. The relative influence of initial microstructure on flow and work-hardening parameters associated with the E-M approach was discussed in the three temperature regimes displayed by P9 and P91 steels.

  5. Heterogeneous chromium catalysts

    OpenAIRE

    2005-01-01

    The present invention relates to a heterogeneous chromium catalyst system for the polymerisation of ethylene and/or alpha olefins prepared by the steps of: (a) providing a silica-containing support, (b) treating the silica-containing support with a chromium compound to form a chromium-based silica-containing support, (c) activating the chromium-based silica-containing support, (d) chemically reducing the activated chromium-based silica-containing support to produce a precursor catalyst, (e) r...

  6. Microstructural and fractographic investigations of a Nb-bearing martensitic 12% chromium-steel (DIN 1.4914) with a lowered nitrogen-content

    International Nuclear Information System (INIS)

    The martensitic steel DIN 1.4914 is favored as structural material for Fast Breeder Reactors. For the use as wrapper tube a new delta-ferrite free melt was developed with a strongly reduced nitrogen - and a low carbon content for achieving a low ductile-to-brittle transition temperature (DBTT). The material was investigated systematically in its microstructure depending on the austenitization and the tempering. The microstructure influences the fracture behaviour of the steel. As a main result the fractures of tensile and impact tested samples are predominatly formed by the inclusions and the secondary precipitates. (orig.)

  7. New structural high strength rationally alloyed steels

    International Nuclear Information System (INIS)

    New developments in high strength structural steels are reported. Properties and perspective fields of application are described for the following materials: austenitic chromium steels with ultra equilibrium nitrogen content, steels with nitrogen martensite structure, microalloyed ferritic-pearlitic steels with decreased concentrations of Mn and Ni, high ductility heat resisting steels, nonmagnetic chromium free Mn-Ni-Cu-V-C steels and iron powder alloys with superhard carbon phases. Steel 02Kh12G14N4YuM is recommended to be used for parts and assemblies of nuclear power plants

  8. Distribution of soluble and precipitated iron and chromium products generated by anodic dissolution of 316L stainless steel and alloy C-22: final report

    Energy Technology Data Exchange (ETDEWEB)

    Estill, J; Farmer, J; Gordon, S; King, K; Logotetta, L; Silberman, D

    1999-08-11

    At near neutral pH and at applied potentials above the threshold potential for localized breakdown of the passive film, virtually all of the dissolved chromium appeared to be in the hexavalent oxidation state (Cr(VI)). In acidic environments, such as crevice solutions formed during the crevice corrosion of 316L and C-22 samples in 4 M NaCl, virtually all of the dissolved chromium appeared to be in the trivalent oxidation state (Cr(III)). These general observations appear to be consistent with the Pourbaix diagram for chromium (Pourbaix 1974), pp. 307-321. At high pH and high anodic polarization (pH {approximately} 8 and 800 mV vs. SHE), the predominate species is believed to be the soluble chromate anion (CrO{sub 4}{sup 2{minus}}). At the same pH, but lower polarization (pH {approximately} 8 and 0 mV vs. SHE), the predominate species are believed to be precipitates such as trivalent Cr(OH){sub 3} {center_dot} n(H{sub 2}O) and hexavalent Cr{sub 2}O{sub 3}. In acidified environments such as those found in crevices (pH < 3), soluble Cr{sup 3+} is expected to form over a wide range of potential extending from 400 mV vs. SHE to approximately 1200 mV vs. SHE. Again, this is consistent with the observations from the creviced samples. In earlier studies by the principal investigator, it has been found that low-level chromium contamination in ground water is usually in the hexavalent oxidation state (Farmer et al. 1996). In general, dissolved iron measured during the crevice experiments appears to be Fe(II) in acidic media and Fe(III) in near-neutral and alkaline solutions (table 3). In the case of cyclic polarization measurements, the dissolved iron measured at the end of some cyclic polarization measurements with C-22 appeared to be in the Fe(III) state. This is probably due to the high electrochemical potential at which these species were generated during the potential scan. Note that the reversal potential was approximately 1200 mV vs. Ag/AgCl during these scans. These

  9. Effect of pulsed treatment with the flows of high-temperature plasma on the increase of corrosion resistance of chromium ferrite -martensite steel in liquid lead

    International Nuclear Information System (INIS)

    Effects of preliminary pulsed plasma treatment on a corrosion resistance of 16Cr-12Mo-W-Si-Nb-V-B ferrite-martensite steel in liquid lead in the conditions of static and dynamic tests at 750 and 659 deg C have been investigated. It was found that plasma-induced modification of the surface layer structure and phase composition decreases a thickness of the oxide film more than 2-3 times, and a liquid-phase surface alloying with Cr or Al decreases the surface corrosion by 3-10 times. Alloying the surface layers with Al up to 13-14 wt.% is found to be resulted in almost full suppression of the steel oxidation in a liquid lead flux at the temperature of 650 deg C and the test duration of 1680 h

  10. Effect of welding thermal cycle and hydrogen concentration on the tendency of chromium-nickel-molybdenum-vanadium steels to brittle failure

    International Nuclear Information System (INIS)

    The effects of welding thermal cycle and hydrogen concentration in metals on the tendency of Cr-Ni-Mo-V steels (15Kh2NMFA, 25KhN3MFA, 35KhN3MFA, 10GN2MFA) to cold cracking are investigated. The samples have been subjected to heat treatment simulating arc and electroslag welding cycles, than the fatigue crack has been formed and fracture toughness in various areas of heat affected zone has been studied. Stress intensity factors after welding thermal cycle as well as the effect of carbon content on the stress intensity factor are studied. The tendency of steels to hydrogen embrittlement is evaluated. It has been determined that cold cracks appear as a result of a slow propagation of microdefects which significantly accelerates in the presence of hydrogen

  11. Tool steels

    DEFF Research Database (Denmark)

    Højerslev, C.

    2001-01-01

    On designing a tool steel, its composition and heat treatment parameters are chosen to provide a hardened and tempered martensitic matrix in which carbides are evenly distributed. In this condition the matrix has an optimum combination of hardness andtoughness, the primary carbides provide...... resistance against abrasive wear and secondary carbides (if any) increase the resistance against plastic deformation. Tool steels are alloyed with carbide forming elements (Typically: vanadium, tungsten, molybdenumand chromium) furthermore some steel types contains cobalt. Addition of alloying elements...... serves primarily two purpose (i) to improve the hardenabillity and (ii) to provide harder and thermally more stable carbides than cementite. Assuming proper heattreatment, the properties of a tool steel depends on the which alloying elements are added and their respective concentrations....

  12. Hexavalent Chromium Workshop

    Science.gov (United States)

    EPA is developing an updated IRIS assessment of hexavalent chromium. This assessment will evaluate the potential health effects of hexavalent chromium from oral and inhalation exposures. An important component of determining the cancer causing potential of ingested hexavalent chr...

  13. A study of the physical and chemical conditions required to determine vanadium in steels by atomic absorption spectrometry also allowing the determination for copper, chromium, nickel and manganese

    International Nuclear Information System (INIS)

    In the determination of the vanadium content of a steel, the height of observation and the stoichiometry of the flame have a considerable influence. Maximum sensitivity is obtained with a height of observation of 12 mm and a reducing flame. The interactions of different cations (Na, K, Mg, Cr, Fe, Cu, Mn, Zn, La) with the vanadium depend on the nature of these cations. The various actions of hydrochloric, nitric and perchloric acids and their iron salts were studied. The results obtained relating to iron-vanadium interactions suggest possible mechanisms of the processes leading to atomisation. A proposal is made for a mixture of three salts: NH4Cl, MgCl2 and LaCl3, whose combined action makes it possible to obtain good results in the determination of the vanadium content of different types of steels. This interaction buffer also allowed the determination of the Mn, Cu, Cr and Ni contents of the same steels, without using iron compensation in the calibration ranges. (author)

  14. Standard practice for determining the susceptibility of stainless steels and related Nickel-Chromium-Iron Alloys to stress-corrosion cracking in polythionic acids

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2010-01-01

    1.1 This practice covers procedures for preparing and conducting the polythionic acid test at room temperature, 22 to 25°C (72 to 77°F), to determine the relative susceptibility of stainless steels or other related materials (nickel-chromiumiron alloys) to intergranular stress corrosion cracking. 1.2 This practice can be used to evaluate stainless steels or other materials in the “as received” condition or after being subjected to high-temperature service, 482 to 815°C (900 to 1500°F), for prolonged periods of time. 1.3 This practice can be applied to wrought products, castings, and weld metal of stainless steels or other related materials to be used in environments containing sulfur or sulfides. Other materials capable of being sensitized can also be tested in accordance with this test. 1.4 This practice may be used with a variety of stress corrosion test specimens, surface finishes, and methods of applying stress. 1.5 This standard does not purport to address all of the safety concerns, if any, ...

  15. Determination of Nitrogen in Chromium Stainless Steel by Spark Source Optical Emission Spectrometry%火花源原子发射光谱法测定铬不锈钢中氮含量的研究与应用

    Institute of Scientific and Technical Information of China (English)

    王化明; 陈学军

    2009-01-01

    The determination of nitrogen in chromium stainless steel by spark source optical emission spectrometry was studied. The optimum conditions for the detection have been experimentally studied to eliminate the spectral interference and matrix effects. Furthermore, many other issues such as sample selection, preparation, set value and on-line analysis were also discussed. The detection range for nitrogen was from 0.00% to 0.073% with a detection limit of 0.0005%. This paper provides an accurate, timely technique for on-line control analysis with good reproducibility.%本文通过实验确定火花源原子发射光谱法测定铬不锈钢样品氮的最佳分析条件,消除光谱干扰和基体效应,制作氮的光谱校准曲线以实现铬不锈钢中氮含量的准确测定,并对铬不锈钢样品选择、制备和定值,现场样品分析等问题进行了讨论.本方法的分析范围在0.00%~0.0730%之间,检出限为0.0005%.该方法用于在线控制分析,准确、及时、重现性好.

  16. Chromium and Genomic Stability

    OpenAIRE

    Wise, Sandra S.; Wise, John Pierce

    2011-01-01

    Many metals serve as micronutrients which protect against genomic instability. Chromium is most abundant in its trivalent and hexavalent forms. Trivalent chromium has historically been considered an essential element, though recent data indicate that while it can have pharmacological effects and value, it is not essential. There are no data indicating that trivalent chromium promotes genomic stability and, instead may promote genomic instability. Hexavalent chromium is widely accepted as high...

  17. 电流密度分配制度对铬系无锡钢耐蚀性的影响%Effect of current density distribution scheme on corrosion resistance of chromium-type tin-free steel

    Institute of Scientific and Technical Information of China (English)

    黄久贵

    2012-01-01

    The differences of surface morphologies of tin-free steels obtained with different current density distribution schemes were studied by scanning electron microscopy. The results showed that there exist many pores on rough surface of the tin-free steel obtained by increasing the current density gradually. The tin-free steel obtained by applying a constant current density has a fine surface with many pores. The surface porosity and morphology of tin-free steel were evidently improved by decreasing the current density gradually. The surface of the chromium coating obtained by applying low and high current density alternately is uniform, smooth, and less porous. The analysis of polarization curves in 3.5wt% NaCl solution and neutral salt spray (NSS) test showed that the tin-free steel obtained by alternating current density has better corrosion resistance than those obtained with other current density distribution schemes. The equations presenting the relationship between NSS test temperature and time of the first rust spot appearance were established for the tin-free steels obtained with different current density distribution schemes.%采用扫描电镜分析了不同电流密度分配制度下所得无锡钢板表面形貌的差异.结果表明,电流密度逐渐增大的分配制度获取的无锡钢表面存在较多孔隙,且镀层表面粗糙.电流密度平均分配时获取的无锡钢表面尽管同样存在较多孔隙,但是镀层表面较为细腻.电流密度逐渐减小的分配制度获取的无锡钢表面孔隙率和状态均明显改善.电流密度交叉式分配制度获取的无锡钢表面孔隙率少,且铬镀层均匀、细腻.根据3.5%(质量分数)NaCl溶液中的极化曲线和中性盐雾试验分析可知,与其他电流密度分配制度相比,交叉式电流密度分配制度获取的无锡钢耐蚀性较好.建立了不同电流密度分配制度下所得无锡钢在中性盐雾试验中的点蚀产生时间与试验温度的方程.

  18. Performance of 9% chromium steel X 10 CrMoVNb 9 1 in short- and long-term tests. Pt. 2

    International Nuclear Information System (INIS)

    The steel X 10 CrMoVNb 9 1 demonstrates an excellent welding performance chiefly due to its relatively low carbon content. The hardness acceptance in the weld deposit is lower than in comparable materials and therefore the susceptibility to cracking following cooling from the operating temperature to room temperature is also lower. Preheating from 200 to 300deg C is sufficient to ensure cold crack-free welding. There is no susceptibility to cracking of the heat influence zone course grain structure with stress-free annealing. The heat influence zones of the welds demonstrate in all areas excellent toughness characteristics even after different types of heat treatment. (orig.)

  19. A numerical approach to predict the long-term creep behaviour and precipitate back-stress evolution of 9-12% chromium steels

    Energy Technology Data Exchange (ETDEWEB)

    Holzer, I.; Cerjak, H. [Graz Univ. of Technology (Austria). Inst. for Materials Science and Welding; Kozeschnik, E. [Vienna Univ. of Technology (Austria). Inst. of Materials Science and Technology; Vienna Univ. of Technology (Austria). Christian Doppler Lab. ' Early Stages of Precipitation'

    2010-07-01

    The mechanical properties of modern 9-12% Cr steels are significantly influenced by the presence and stability of different precipitate populations. These secondary phases grow, coarsen and, sometimes, dissolve again during heat treatment and service, which leads to a remarkable change in the obstacle effect of these precipitates on dislocation movement. In the present work, the experimentally observed creep rupture strength of a modified 9-12% Cr steel developed in the European COST Group is compared to the calculated maximum obstacle effect (Orowan threshold stress) caused by the precipitates present in the investigated alloy for different heat treatment conditions. It is shown that the differences in creep rupture strength caused by different heat treatments disappear after long time service. This observation is discussed on the basis of the calculated evolution of the precipitate microstructure. The concept of boosting long-term creep rupture strength by maximizing the initial creep strength with optimum quality heat treatment parameters for precipitation strengthening is critically assessed. (orig.)

  20. Corrosion of various ferritic steels in an isothermal sodium loop system

    International Nuclear Information System (INIS)

    Ferritic chromium-molybdenum steels with chromium contens of 1 wt% up to 12 wt% have been exposed for 8370 h to flowing sodium at 5500C. The oxygen content of the sodium was 6-7 ppm by weight. Weight measurements, carbon analyses and metallographic examinations were carried out. The low chromium steels show weight loss and decarburisation. The high chromium steels show weight gain and carburisation. The crossover point is at about 5 wt% Cr. The composition at the utmost surface (< 10 μm) of the various steels tend to about 8 wt% chromium, about 2 wt% nickel and 0.02-0.09 wt% carbon. Sodium chromite crystals were present on the steels with a chromium content of 5 wt% or more. At the exposed surface of the 21/4 wt% chromium steel sodium chromite crystals were found locally. (orig.)

  1. Caracterização por XPS de filmes passivos formados sobre aços de baixa liga em meio de bicarbonato XPS characterization of passive films formed on mild steels in bicarbonate medium

    Directory of Open Access Journals (Sweden)

    Valéria Almeida Alves

    2005-03-01

    Full Text Available Passive films formed in bicarbonate solutions on carbon steel, chromium steel and high speed steel have been characterized by XPS. The passive films formed on chromium and high speed steels showed superior protective properties than those formed on carbon steel. It was confirmed by XPS that the steel composition influences the passive film composition. Chromium oxide and hydroxide, as well as molybdenum and tungsten oxides and hydroxides are present in the passive film of chromium steel and high speed steel, respectively, besides iron oxide and hydroxide. The more complex composition of the oxide film on high speed steel explains its electrochemical behaviour and highest corrosion resistance.

  2. Metallurgical investigations of microstructure and behaviour of high-alloyed manganese-chromium austenitic steels for generator-rotor retaining rings

    International Nuclear Information System (INIS)

    The austenite steel X 55 MnCr(N)18K used for generator retaining rings shows minimum toughness, a purely intercrystalline fracture course and an eutectoid transformation at the grain boundaries after annealing at 5250C of cold-formed and of solution annealed material. A retaining ring broken in the test area shows a similar fracture pattern, mainly in the radial direction of stress. This retaining ring which had been cold-formed to high strength and thus was very greatly anisotropic in its mechanical properties accordingly shows specially low toughness values in the radial direction. From SEM and STEM/EDX investigations of the damage material and of rings from the same melt, it can be assumed that as a result of the coincidence of unfavourable conditions - very high cold-streching and low nitrogen content - commencing eutectoid dissociation of the metastable austenite occured. The extremely low toughness values of the damage material, especially with radial sample positions, can thus be deduced from the high anisotropy of the mechanical properties and an metallurgical peculiarity due to manufacture. (Author)

  3. Features of phase composition of stainless austenitic steels and possibility of selection tubes of these steels in accordance with their steel grades by means of eddy current method

    International Nuclear Information System (INIS)

    Studies on mechanical, magnetic and electric characteristics of some types of chromium-nickel and chromium-nickel-molybdenum austenitic steels used for manufacturing hot-rolled tubes are carried out. A possibility of nondestructive control of stainless austenitic steel by grades is disclosed. A mock-up of an eddy device with a superposed transformer for measurements on samples of tubes is described

  4. Oxidation of chromium telluride

    International Nuclear Information System (INIS)

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation

  5. Oxidation of chromium telluride

    Energy Technology Data Exchange (ETDEWEB)

    Pakhomovskaya, N.S.; Iorga, E.V.; Sheveleva, T.F.; Solov' eva, A.E.

    1986-03-01

    The authors study the interaction between chromium telluride and oxygen at elevated temperatures in view of its application in semiconductor technology. Thermodynamic analysis of the oxidation process and experimental data showed that the alloys of chromium telluride suffer oxidation in the presence of even traces of oxygen in a gaseous medium. Chromium telluride oxidation is a complex process that gives rise to various oxides and is accompanied by partial sublimation.

  6. Investigations of the oxidation-induced service life of chromium steels for high temperature fuel cell application (SOFC); Untersuchungen zur oxidationsbedingten Lebensdauer von Chromstaehlen fuer die Anwendung in der Hochtemperaturbrennstoffzelle (SOFC)

    Energy Technology Data Exchange (ETDEWEB)

    Ertl, S.T.

    2006-08-17

    The increasing energy consumption of future automobiles should be covered by a solid oxide fuel cell (SOFC) used as an additional energy supply (auxiliary power unit). The application of a SOFC with about 5 kW power in cars requires small size, low weight and an economic fabrication. To achieve this goal the interconnector and the metallic anode substrate (depending on an alternative concept of construction) should be manufactured out of thin Crofer22APU, a high chromium ferritic steel. The scale formation mechanisms on Crofer22APU sheets, wires and powder metallurgical produced foils of different thicknesses were investigated in several atmospheres of water vapour/hydrogen at 800 and 900 C, simulating the anode conditions. For scale characterization a number of conventional analysis techniques such as optical metallography, scanning electron microscopy and X-ray diffraction were used in combination with deflection testing in monofacial oxidation and two-stage oxidation studies using {sup 18}O and H{sub 2} {sup 18}O tracer. With these results a theoretical model for the determination of lifetime was developed for Crofer22APU components in simulated anode gas. It was found that the lifetime at a given temperature depends not only on the surface-to-volume ratio, but also on the geometry of the component (e.g. sheet or wire). The critical Cr content required for breakaway oxidation depends on microcrack formation in the surface oxide scale, which occurs on ridges of a sheet during thermal cycling. The development of a metallic interconnector and a metallic anode substrate requires measures to avoid interdiffusion between the alloy and the bordering nickel-YSZ (yttrium stabilized zirconia) cermet of the anode, or depending on the conception of the stack, the bordering nickel-YSZ cermet of the anode functional layer. Therefore the suitability of preoxidation layers after different preoxidation conditions was tested. It was found that the inhibition of the interdiffusion

  7. Hair chromium concentration and chromium excretion in tannery workers.

    OpenAIRE

    Saner, G; Yüzbasiyan, V; Cigdem, S

    1984-01-01

    Hair and urine samples were collected from 34 male tannery workers and from 12 normal adults. Eighteen of the workers dealt directly with chromium and the remaining 16 (controls) worked in the offices and kitchen of the same factory. All were found to be clinically healthy. Chromium was determined by flameless atomic absorption spectroscopy. When compared with normal adult values, urinary chromium concentration, Cr/Creatinine ratio, daily chromium excretion, and hair chromium, concentrations ...

  8. High-Purity Chromium Targets

    OpenAIRE

    Rudoy, A.; Milman, Yu.; Korzhova, N.

    1995-01-01

    A procedure for producing large-scale chromium ingots by means of induction-arc melting was developed. From the high-purity, low-alloyed chromium ingots obtained, chromium targets were produced by of thermoplastic treatment techniques. The method of electron-beam evaporation of high-purity chromium was also used for production of targets.

  9. Contingency plans for chromium utilization. Publication NMAB-335

    International Nuclear Information System (INIS)

    The United States depends entirely on foreign sources for the critical material, chromium, making it very vulnerable to supply disruptions. This vulnerability results because chromium is essential for the fabrication of corrosion-resisting steels and high-temperature, oxidation-resisting alloys in applications that are vital to the nation's technological well-being; because no substitutes are known for these materials in those applications; and because the known, substantial deposits of chromite ore are only in a few geographical locations that could become inaccessible to the United States as a result of political actions. The effectiveness of programs such as stockpiling, conservation, and research and development for substitutes to reduce the impact of disruption of imports of chromite and ferrochromium are discussed. Alternatives for decreasing chromium consumption also are identified for chromium-containing materials in the areas of design, processing, and substitution

  10. Chromium speciation in rainwater: temporal variability and atmospheric deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kieber, R.J.; Willey, J.D.; Zvalaren, S.D. [University of North Carolina at Wilmington, Wilmington, NC (United States). Dept. of Chemistry

    2002-12-15

    Chromium is released into the atmosphere by a variety of anthropogenic activities which include steel manufacturing, leather tanning, wood presentation and fossil fuel combustion. The concentrations of the various chromium species were determined in 89 rainwater samples collected in Wilmington, NC from October 1, 1999 to December 31, 2001. Volume weighted annual average concentrations of Cr{sub total}, particulate Cr, Cr(III)(aq), and Cr(VI)(aq) were 4.6, 2.2, 0.8 and 1.2 nM, respectively. There was distinct seasonal and diurnal variability in the concentrations of the various chromium species. Chromium emissions to the global atmosphere by both natural and anthropogenic sources are estimated to be 2.2 x 10{sup 9} mol/yr. Using rainwater concentration data along with other published rainwater Cr concentrations and an estimate for total global annual rain, the total global flux of chromium removed from the atmosphere via wet deposition is 2.1 x 10{sup 9} mol/yr. This represents complete removal of Cr and indicates that essentially all chromium released into the global atmosphere is removed via rain. About half this chromium is dissolved with roughly equal concentrations of toxic Cr(VI) and relatively harmless Cr(III) species. 48 refs., 4 figs., 3 tabs.

  11. Investigations of the Dephosphorization of Liquid Iron Solution Containing Chromium and Nickel

    Science.gov (United States)

    Karbowniczek, Miroslaw; Kawecka-Cebula, Elzbieta; Reichel, Jan

    2012-06-01

    The most up-to-date trends in stainless steel production—aiming at the reduction of production costs—consist of the substitution of steel scrap by hot metal, coming from the reduction of iron-chromium ores. This process requires a more extensive dephosphorization. The dephosphorization process, when applied to chromium steels, requires slag with high dephosphorization properties, as either chromium or chromium oxide entering the slag decreases distinctly the efficiency of the process. The results of laboratory investigations on the dephosphorization of liquid iron solutions containing chromium and nickel are presented. In particular, the study was focused on the selection of the optimal slag composition and the way the slag should be added. The slags based on calcium and fluorite with cryolite additions were considered. It was shown that the variables with the greatest impact on the dephosphorization process include chromium and nickel levels, temperature, and slag basicity. A statistical analysis was performed and regression equations were set. The results may be of use for the design of new methods of production of high-chromium steels.

  12. Substoichiometric extraction of chromium

    International Nuclear Information System (INIS)

    Substoichiometric extraction of chromium with tetraphenylarsonium chloride (TPACl), tri-n-octylamine (TNOA), diethylammonium diethyldithiocarbamate (DDDC) and ammonium pyrrolidinedithiocarbamate (APDC) was examined in detail. Chromium can be extracted substoichiometrically in a pH range, which is 1.1-2.6 for the TPACl compound, 0.6-2.3 for the TNOA compound, 5.1-6.4 for the DDDC chelate and 3.9-4.9 for the APDC chelate. Chromium in high-purity calcium carbonate, Orchard Leaves (NBS SRM-1571) and Brewers Yeast (NBS SRM-1569) was determined by neutron activation analysis combined with substoichiometric extraction by DDDC and APDC. The values of 2.0+-0.02 ppm and 2.6+-0.2 ppm were obtained for Brewers Yeast and Orchard Leaves, respectively. These values were in good agreement with those reported by NBS. The reaction mechanism and the reaction ratio between hexavalent chromium and dithiocarbamate are also discussed. (author)

  13. Chromium in diet

    Science.gov (United States)

    ... Chromium deficiency may be seen as impaired glucose tolerance. It occurs in older people with type 2 ... PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health Topics Minerals Browse the Encyclopedia ...

  14. The carcinogenicity of chromium

    OpenAIRE

    Norseth, Tor

    1981-01-01

    The carcinogenicity of chromium compounds is reviewed with specific attention to the gaps in knowledge for risk estimation and research needs. The most important problems at present are whether trivalent chromium compounds cause cancer, and whether there is a difference in cancer causing effects between the soluble and the slightly soluble hexavalent compounds in the practical exposure situation. Dose estimates for risk estimation based on epidemiological investigations are also lacking. Pres...

  15. Thermal fatigue of high chromium steel rolls

    OpenAIRE

    Valverde Montraveta, Gerard

    2013-01-01

    Within the master work the phenomenon of appearance of firecracks on the surface of the work rolls that occur during hot rolling of flat products in the case of regular rolling conditions and in the case of the rolling mill stalls was investigated. During hot rolling work rolls are subjected to successive heating and cooling conditions. Their surface is exposed to rapid temperature changes due to the contact with hot rolled material and due to cold water used for rolls cooling. These cyclic h...

  16. Effect of tritium on corrosion behavior of chromium in 0.01 N sulfuric acid solution

    International Nuclear Information System (INIS)

    The effects of tritium on the corrosion behavior of chromium in 0.01 N sulfuric solution have been investigated in the present study. Electrochemical experiments have been carried our for pure chromium. At first, the concentration dependence of sulfuric acid solution on anodic polarization behavior of chromium was experimented, resulting in that 0.01 N one was found appropriate. The dependence of both dissolved oxygen and tritium concentration on anodic behavior of chromium were performed. It was found from that the self-passivation of chromium induced by dissolved oxygen was inhibited in tritiated solution resulting in the enhancement of the corrosion. As a consequence it is highly likely that the elution of chromium by highly oxidative radiolysis products would explain the passivation inhibitory effect of SUS304 stainless steel observed in tritiated solutions

  17. Obtaining decorative chromium plating from trivalent chromium solutions

    OpenAIRE

    Óscar Javier Suárez García

    2010-01-01

    The present work was aimed at a qualitative evaluation, in the laboratory, of different alternatives for assembling and operating a trivalent chromium bath for decorative chromium plating. Different chromium concentration solutions and different complexing agents were used. The initial result of this analysis was that chloride, formate and acetate solutions produced the best results. Solution preparation conditions were evaluated: temperature, chromium III complex formation time and also ...

  18. The analytical biochemistry of chromium.

    OpenAIRE

    Katz, S A

    1991-01-01

    The essentiality and carcinogenicity of chromium depend on its chemical form. Oxidation state and solubility are particularly important in determining the biological effects of chromium compounds. For this reason, total chromium measurements are of little value in assessing its nutritional benefits or its toxicological hazards. Aqueous sodium carbonate-sodium hydroxide solutions have been successfully used for extracting hexavalent chromium from a variety of environmental and biological matri...

  19. Chromium in potatoes

    International Nuclear Information System (INIS)

    Chromium concentration in potatoes was determined, and tubes were labeled either intrinsically or extrinsically with radioactive chromate (51Cr). A labeled chromium complex was isolated from preparations of raw, baked, or fried potatoes and chromatographed on gel permeation media. Potato pulp and peel contained 1.63 and 2.70 μg of Cr/g tissue, respectively. There was no correlation between the two, nor did they respond similarly to changes of variety or locations. No significant differences were apparent in relative migration of the isolated complexes except between raw and cooked extrinsically labeled preparations

  20. Chromium and aging

    Science.gov (United States)

    Aging is associated with increased blood glucose, insulin, blood lipids, and fat mass, and decreased lean body mass leading to increased incidences of diabetes and cardiovascular diseases. Improved chromium nutrition is associated with improvements in all of these variables. Insulin sensitivity de...

  1. Investigations on the Oxidation of Iron-chromium and Iron-vanadium Molten Alloys

    OpenAIRE

    Wang, Haijuan

    2010-01-01

    With the progress of high alloy steelmaking processes, it is essential to minimize the loss of valuable metals, like chromium and vanadium during the decarburization process, from both economic as well as environmental view points. One unique technique to realize this aim, used in the present work, is the decarburization of high alloy steel grades using oxygen with CO2 in order to reduce the partial pressure of oxygen. In the present work, the investigation on the oxidation of iron-chromium a...

  2. Microstructure and transformation kinetics in bainitic steels

    OpenAIRE

    Luzginova, N.V.

    2008-01-01

    With the aim of reaching a better understanding of the microstructure evolution and the overall phase transformation kinetics in hyper-eutectoid steels a commercial SAE 52100 bearing steel and 7 model alloys with different concentrations of chromium, cobalt and aluminum have been studied in this work, both experimentally and theoretically. The effect of alloying elements, Cr, Co and Al, on different processes occurring during heat treatment of hyper-eutectoid steels (cementite spheroidization...

  3. Studies of chromium gettering

    International Nuclear Information System (INIS)

    Preliminary results have shown that hydrogen pumping by chromium is a surface effect. Unlike with titanium, the getter material used in many present day tokamaks, there is no significant diffusion into the bulk. Additional experiments have been carried out to measure the basic characteristics of chromium films for gases of interest in tokamak research. These gases include deuterium, oxygen and nitrogen. A vacuum system is described which allowed precise control of the test gas, a constant wall temperature and determination of the projected getter surface area. A quadrupole mass spectrometer, rather than simply a total pressure gauge, was utilized to measure the partial pressure of the test gas as well as the residual gas composition in the system. A quartz crystal monitor was used to measure film thickness. Pumping speeds and sticking coefficients are given as a function of surface coverage for each test gas. A comparison will be made with titanium films deposited in the same vacuum system and under similar conditions

  4. Bioleaching of hexavalent chromium from soils using acidithiobacillus thiooxidans

    OpenAIRE

    Fonseca, Bruna; Rodrigues, Joana; Queiroz, A.M.; Tavares, Teresa

    2010-01-01

    The continuous and growing degradation of the environment, due to several anthropogenic activities, is a main concern of the scientific community. Consequently, the development of low cost techniques to clean air, water and soils are under intense investigation. In this study, the focused problem is the soil contamination by hexavalent chromium, which is known for its several industrial applications - production of stainless steel, textile dyes, wood preservation and leather tanning - its hig...

  5. Characterisation of chromium nitride films produced by PVD techniques

    OpenAIRE

    Barata, A.; CUNHA L.; Moura, C.

    2001-01-01

    Chromium nitride thin films have been deposited on stainless steel substrates by r.f. reactive magnetron sputtering. The influence of process parameters such as substrate bias and partial pressure of reactive gas have been investigated. The characterisation of the coatings was performed by X-ray diffraction (XRD), Raman Spectroscopy (RS) and nano-indentation experiments. These studies allow to analyse the influence of deposition parameters in crystal phases, crystal orientationytextu...

  6. Catalytic Spectrophotometric Determination of Chromium

    OpenAIRE

    STOYANOVA, Angelina Miltcheva

    2005-01-01

    The catalytic effect of chromium(III) and chromium(VI) on the oxidation of sulfanilic acid by hydrogen peroxide was studied. The reaction was followed spectrophotometrically by measuring the absorbance of the reaction product at 360 nm. Under the optimum conditions 2 calibration graphs (for chromium(III) up to 100 ng mL-1, and for chromium(VI) up to 200 ng mL-1) were obtained, using the ``fixed time'' method with detection limits of 4.9 ng mL-1 and 3.8 ng mL-1, respectively...

  7. Corrosion of austenitic steel in sodium loops

    International Nuclear Information System (INIS)

    The possibility of predicting corrosion effects for austenitic steel exposed to liquid sodium with an analytical diffusion model is presented. The analytically predicated corrosion effects are compared with experimental measurements of corrosion effects achieved in an accurately controlled sodium loop. The diffusion model is described with figures showing disc sample weight loss and sodium flow guidance tube chromium and nickel profiles. Finally, the concentration profile in the fuel rod wall (diffusion model) is presented for iron, chromium and nickel

  8. Toxicity assessment and geochemical model of chromium leaching from AOD slag.

    Science.gov (United States)

    Liu, Bao; Li, Junguo; Zeng, Yanan; Wang, Ziming

    2016-02-01

    AOD (Argon Oxygen Decarburization) slag is a by-product of the stainless steel refining process. The leaching toxicity of chromium from AOD slag cannot be ignored in the recycling process of the AOD slag. To assess the leaching toxicity of the AOD slag, batch leaching tests have been performed. PHREEQC simulations combined with FactSage were carried out based on the detailed mineralogical analysis and petrophysical data. Moreover, Pourbaix diagram of the Cr-H2O system was protracted by HSC 5.0 software to explore the chromium speciation in leachates. It was found that AOD slag leachate is an alkaline and reductive solution. The Pourbaix diagram of the Cr-H2O system indicated that trivalent chromium, such as Cr(OH)4(-), is the major chromium species in the experimental Eh-pH region considered. However, toxic hexavalent chromium was released with maximum concentrations of 30 µg L(-1) and 18 µg L(-1) at L/S 10 and 100, respectively, during the earlier leaching stage. It concluded that the AOD slag possessed a certain leaching toxicity. After 10 d of leaching, trivalent chromium was the dominant species in the leachates, which corresponded to the results of PHREEQC simulation. Leaching toxicity of AOD slag is based on the chromium speciation and its transformation. Great attention should be focused on such factors as aging, crystal form of chromium-enriched minerals, and electrochemical characteristics of the leachates. PMID:26583286

  9. Stainless steel denitriding with slag

    International Nuclear Information System (INIS)

    Calculation and experimental methods were used to investigate the process of titanium nitride formation when alloying chromium nickel stainless steels with titanium. At common concentrations of titanium and nitrogen, titanium nitrides were observed to be precipitated from the melt into slag in amounts of 0.1% and more. The laboratory study of the slag influence of the process of steel refining from titanium nitrides showed that the slag containing calcium, aluminium and magnesium oxides is favourable to the denitriding of steel. In addition, the possibility of direct transition of dissolved nitrogen from the metal into the slag is revealed. 7 refs., 1 fig., 2 tabs

  10. Microbial Diversity of Chromium-Contaminated Soils and Characterization of Six Chromium-Removing Bacteria

    Science.gov (United States)

    He, Zhiguo; Hu, Yuting; Yin, Zhen; Hu, Yuehua; Zhong, Hui

    2016-06-01

    Three soil samples obtained from different sites adjacent to a chromium slag heap in a steel alloy factory were taken to examine the effect of chromium contamination on soil bacterial diversity as determined by construction of 16S rDNA clone libraries and sequencing of selected clones based on restriction fragment length polymorphism (RFLP) analysis. Results revealed that Betaproteobacteria, Gammaproteobacteria, Firmicutes, and Alphaproteobacteria occurred in all three soil samples, although the three samples differed in their total diversity. Sample 1 had the highest microbial diversity covering 12 different classes, while Sample 3 had the lowest microbial diversity. Strains of six different species were successfully isolated, one of which was identified as Zobellella denitrificans. To our knowledge, this is the first report of a strain belonging to the genus Zobellella able to resist and reduce chromium. Among all isolates studied, Bacillus odysseyi YH2 exhibited the highest Cr(VI)-reducing capability, with a total removal of 23.5 % of an initial Cr(VI) concentration of 350 mg L-1.

  11. CHROMIUM, METABOLIC SYNDROME AND DIABESITY

    Science.gov (United States)

    Suboptimal intakes of the essential nutrient, chromium, are characterized by elevated blood glucose, insulin resistance, obesity, hypertriglyceridemia, and low HDL. These are also signs and symptoms of the metabolic syndrome. Improvements due to increased intake of chromium are related to the degr...

  12. Groundwater contaminant by hexavalent chromium

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, C. [Univ. of Texas, Austin, TX (United States)

    1995-11-01

    Oxidation of trivalent chromium to hexavalent chromium has been investigated as a function of total manganese in soils as well as various incubation conditions. Chromium and manganese contents were analyzed by atomic absorption (graphite furnace and flame emission respectively) following acid digestion. Total hexavalent chromium generation capacity was determined by addition of 0.001 M CrCL3, incubation, and analysis by s-diphenyl carbazide. Samples were then leached with CaSO{sub 4} and MgSO{sub 4} and incubated in various environments (oven, freeze-drier, field moist, ultrafreeze) to test for geogenic generation of Cr(IV). The degree of geogenic generation of hexavalent chromium was compared with total Mn and Cr content as well as hexavalent generational capacity.

  13. Role of paramagnetic chromium in chromium(VI)-induced damage in cultured mammalian cells.

    OpenAIRE

    Sugiyama, M

    1994-01-01

    Chromium(VI) compounds are known to be potent toxic and carcinogenic agents. Because chromium(VI) is easily taken up by cells and is subsequently reduced to chromium(III), the formation of paramagnetic chromium such as chromium(V) and chromium(III) is believed to play a role in the adverse biological effects of chromium(VI) compounds. The present report, uses electron spin resonance (ESR) spectroscopy; the importance of the role of paramagnetic chromium in chromium(VI)-induced damage in intac...

  14. Determination of chromium, iron, zinc and calcium contents in pastes commercialized at Sao Paulo, Brazil

    International Nuclear Information System (INIS)

    Foods, in particular pastes, in the industrial manufacture process are in contact with equipment made of stainless steel, containing Cr, fe and Zn in their structures. The aim of this study is to verify Cr, Fe and Zn migration from the stainless steel equipment to the food during the industrial process. Instrumental neutron activation analysis was applied to determine the concentrations of Cr, Fe, Zn and Ca in four brands of pastes. Only the migration of chromium was be observed. (author)

  15. Corrosion of alloy steels in oil field fluids

    International Nuclear Information System (INIS)

    Laboratory and field tests have been conducted on two low alloy and two higher alloy steels at a range of brine salinities and sulfide contents typical of oil well production fluids. AISI types 4130 and 4340 show the same behavior in these fluids as mild steel. AISI type 410 stainless steel and 9% chromium - 1% molybdenum steel corrode at rates as great as that of mild steel at higher chloride or sulfide concentrations. Special corrosion inhibitors are required for higher alloy steels when they are exposed to these conditions

  16. Effect of machining on the deformability of steel in surface-active medium at lower temperatures

    International Nuclear Information System (INIS)

    The effect of some machining methods of carbon steel, chromium steel, and chromium nickel steel, and that of low temperatures on the principle characteristics of formability during impact bending in air and a surface-active environment have been studied. The temperature decrease from the ambient to -80 deg is shown to reduce steel formability as evaluated by deflection (f) and to increase the forming force. The variation of these characteristics with lowering temperature, however, is greatly affected by machining process conditions. The FRHT (Friction-Hardening Treatment) on the white layer assures minimum ductility losses, and increases steel strength at low temperatures both in air and in the surface-active environment

  17. Fate and transport of chromium through soil

    International Nuclear Information System (INIS)

    Chromium chemistry relevant to the problem facing state of New Jersey (Usa) was examined. Transport of chromium through soil depends on its chemical forms. Transformation of chromium within bulk of soil depends on soil constituents, soil condition, such as pH, Eh and organic compounds applied onto soil or present in soil. Total chromium in soil can be determined. Speciation of chromium based on ionization, hydrolysis, complex formation, redox reactions and adsorption is predicted using MINIQ program

  18. Release of Chromium from Orthopaedic Arthroplasties

    OpenAIRE

    Afolaranmi, G.A.; Tettey, J; Meek, R.M.D; Grant, M.H

    2008-01-01

    Many orthopaedic implants are composed of alloys containing chromium. Of particular relevance is the increasing number of Cobalt Chromium bearing arthroplasies being inserted into young patients with osteoarthritis. Such implants will release chromium ions. These patients will be exposed to the released chromium for over 50 years in some cases. The subsequent chromium ion metabolism and redistribution in fluid and tissue compartments is complex. In addition, the potential biological effects o...

  19. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...... is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river...

  20. Characterisation of exposure to total and hexavalent chromium of welders using biological monitoring.

    NARCIS (Netherlands)

    Scheepers, P.T.J.; Heussen, G.A.; Peer, P.G.M.; Verbist, K.; Anzion, R.; Willems, J.

    2008-01-01

    Inhalation exposure to total and hexavalent chromium (TCr and HCr) was assessed by personal air sampling and biological monitoring in 53 welders and 20 references. Median inhalation exposure levels of TCr were 1.3, 6.0, and 5.4 microg/m(3) for welders of mild steel (MS, <5% alloys), high alloy st

  1. Softening processes in the heat-affected zone of the highly creep-resistant chromium steel X 10 CrMoVNb 9 1 in welded joints and in simulation specimens

    International Nuclear Information System (INIS)

    The study reported here investigates the thermal conditions that lead to 'softening' processes in the HAZ of the steel grade X 10 CrMoVNb 9 1. The experiments are carried out with welds encountered in practice and with simulation specimens. The causes of property changes in the HAZ are discussed on the basis of electron microscopic data, and the hardness and maximum tensile strain in short-time creep tests are determined, as well as the creep behaviour of the welds. It is shown that the processes occurring in the HAZ have important effects on the creep behaviour of the welds under transverse stress. (orig.)

  2. Corrosion, ion release and Mott–Schottky probe of chromium oxide coatings in saline solution with potential for orthopaedic implant applications

    Science.gov (United States)

    Ogwu, A. A.; Oje, A. M.; Kavanagh, J.

    2016-04-01

    We report our investigation on chromium oxide thin film coatings that show a negligible ion release during electrochemical corrosion testing in saline solution. The chemical constituents of the films prepared by reactive magnetron sputtering were identified to be predominantly Cr2O3 based on Raman spectroscopy anti-symmetric stretching vibration modes for CrIII–O and other peaks and an FTIR spectroscopy E u vibrational mode at 409 cm‑1. X-ray photoelectron spectroscopy, multiplet fitting for 2P 3/2 and 2P 1/2 states also confirmed the predominantly Cr2O3 stoichiometry in the films. The prepared chromium oxide coatings showed superior pitting corrosion resistance compared to the native chromium oxide films on bare uncoated stainless steel when tested under open circuit potential, potentiodynamic polarisation and cyclic voltammetry in saline solution. The chromium ion released into solution during the corrosion testing of stainless steel substrates coated with chromium oxide coatings was found to be negligibly small based on atomic absorption spectroscopy measurements. Our Mott–Schottky analysis investigation showed that the negligibly small ion release from the chromium oxide coated steel substrates is most likely due to a much lower defect density on the surface of the deposited coatings compared to the native oxide layer on the uncoated steel substrates. This opens up the opportunity for using chromium oxide surface coatings in hip, knee and other orthopaedic implants where possible metal ion release in vivo still poses a great challenge.

  3. The adhesion of hot-filament CVD diamond films on AISI type 316 austenitic stainless steel

    NARCIS (Netherlands)

    Buijnsters, J.G.; Shankar, P.; Enckevort, W.J.P. van; Schermer, J.J.; Meulen, J.J. ter

    2004-01-01

    Steel ball indentation and scratch adhesion testing of hot filament chemical vapour deposited diamond films onto AISI type 316 austenitic stainless steel substrates using two different interlayer systems, namely chromium nitride and borided steel, have been investigated. In order to compare the adhe

  4. Chromium reduction in Pseudomonas putida.

    OpenAIRE

    Ishibashi, Y.; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells.

  5. Chromium reduction in Pseudomonas putida.

    Science.gov (United States)

    Ishibashi, Y; Cervantes, C; Silver, S

    1990-01-01

    Reduction of hexavalent chromium (chromate) to less-toxic trivalent chromium was studied by using cell suspensions and cell-free supernatant fluids from Pseudomonas putida PRS2000. Chromate reductase activity was associated with soluble protein and not with the membrane fraction. The crude enzyme activity was heat labile and showed a Km of 40 microM CrO4(2-). Neither sulfate nor nitrate affected chromate reduction either in vitro or with intact cells. PMID:2389940

  6. Surface modified stainless steels for PEM fuel cell bipolar plates

    Science.gov (United States)

    Brady, Michael P [Oak Ridge, TN; Wang, Heli [Littleton, CO; Turner, John A [Littleton, CO

    2007-07-24

    A nitridation treated stainless steel article (such as a bipolar plate for a proton exchange membrane fuel cell) having lower interfacial contact electrical resistance and better corrosion resistance than an untreated stainless steel article is disclosed. The treated stainless steel article has a surface layer including nitrogen-modified chromium-base oxide and precipitates of chromium nitride formed during nitridation wherein oxygen is present in the surface layer at a greater concentration than nitrogen. The surface layer may further include precipitates of titanium nitride and/or aluminum oxide. The surface layer in the treated article is chemically heterogeneous surface rather than a uniform or semi-uniform surface layer exclusively rich in chromium, titanium or aluminum. The precipitates of titanium nitride and/or aluminum oxide are formed by the nitriding treatment wherein titanium and/or aluminum in the stainless steel are segregated to the surface layer in forms that exhibit a low contact resistance and good corrosion resistance.

  7. Welding of high manganese- and carbon steels

    International Nuclear Information System (INIS)

    Technology and conditions of welding of high manganese and carbon steel by a resistance welding technique using an intermediate part are developed. Austenitic chromium-nickel 12Kh18N10T steel is chosen as a material of the intermediate part. The recommended welding conditions insure a high quality of the weld joint in terms of metal structure and its mechanical properties. It is the basic metal of the joint that fractures under mechanical testing

  8. Iodine adsorption on steel in helium

    International Nuclear Information System (INIS)

    The equilibrium loading of iodine on low chromium alloy steel as functions of iodine partial pressure, temperature, and metal surface conditions were measured. Desorption rates as functions of temperature and He purity were found and the hazards of iodine release as related to licensing and operation were studied

  9. Hydrogen permeation through chromium

    International Nuclear Information System (INIS)

    Steady state and non-steady state measurements of hydrogen permeation through metallic chromium are reported. The experiments have been conducted by use of hydrogen and deuterium within a pressure range of 10-8 - 1 bar and temperatures between 600 - 8000C. Numerical values for the physical quantities permeability, diffusion constant and solubility could be derived. At an upstream pressure above around 10-3 bar classical Sieverts-low was found (permeation rate proportional √p) with activation energies Qsub(perm) = 65 kJoule/mole, Qsub(Diff) = 4-8 kJoule/mole, Qsub(Sol) = 57-61 kJoule/mole for the respective processes involved. The isotopic effect between H and D of the permeabilities could be represented by a factor of 1,5 independence on temperature. All non steady-state measurements could be approximated reasonably well by classical diffusion kinetics. Below up-stream pressures of approx.= 10-7 bar the kinetics was no longer diffusion controlled, the dependence on up-stream pressure changed from √p -> p, the activation energy for permetation increased to 127 kJoule/mole and the isotopic factor resulted in about 2-3. (orig.)

  10. Development of oxide dispersion strengthened 2205 duplex stainless steel composite

    OpenAIRE

    Oladayo OLANIRAN; Peter Apata OLUBAMBI; Benjamin Omotayo ADEWUYI; Joseph Ajibade OMOTOYINBO; Ayodeji Ebenezar AFOLABI; Davies FOLORUNSO; Adekunle ADEGBOLA; Emanuel IGBAFEN

    2015-01-01

    Composites of duplex stainless steel were produced by oxide dispersion strengthening with comparatively improved mechanical properties by hot press sintering of partially stabilized Zirconia (PSZ, 3% yttria, mole fraction) dispersion in 2205 duplex stainless steels. Ceramic oxide was added as reinforcement, while chromium (Cr) and Nickel (Ni) were incorporated to maintain the austenitic/ferritic phase balance of the duplex stainless steel. The powders and sintered were characterized in detail...

  11. DEVELOPMENTS IN THE FIELD OF STEEL AND CAST IRON

    OpenAIRE

    Ten, E. B.; V. D. Belov

    2015-01-01

    The article describes the use of a number of promising casting technologies applied to produce the castings of steel and cast iron with special properties. Such as, technology of centrifugal casting of large-size workpieces made of steel, forecasting method composition of slag in the smelting of high-manganese steels, method of complex modifying chromium cast irons, analysis of properties of perspective high-alloy aluminium cast iron.

  12. DEVELOPMENTS IN THE FIELD OF STEEL AND CAST IRON

    Directory of Open Access Journals (Sweden)

    E. B. Ten

    2015-05-01

    Full Text Available The article describes the use of a number of promising casting technologies applied to produce the castings of steel and cast iron with special properties. Such as, technology of centrifugal casting of large-size workpieces made of steel, forecasting method composition of slag in the smelting of high-manganese steels, method of complex modifying chromium cast irons, analysis of properties of perspective high-alloy aluminium cast iron.

  13. Alumina Fiber-Reinforced 9310 Steel Metal Matrix Composite for Rotorcraft Drive System Components Project

    Data.gov (United States)

    National Aeronautics and Space Administration — AISI 9310 nickel-chromium-molybdenum alloy steel is used extensively in military helicopter rotor shafts and gears. This reliable alloy provides excellent fatigue...

  14. Study of the reasons of chrome-plated steel embrittlement

    International Nuclear Information System (INIS)

    To study the reasons of embrittement, the mechanical characteristics and hydrogen content in high-strength steel (tensile strength approximately 2O0 kgf/mm2) during electrolytic chrome-plating from a standard electrolyte (60 μm), heating (200 deg, 2 hrs) and aging (20 deg, 7 days) of the chrome-plated samples have been tested. The hydrogen content in the steel base after chromium removal is measured using the method of vacuum extraction at a temperature of 400 deg. The results obtained permit to describe the mechanism of the decrease in service characteristics of chrome-plated steel. The presence of brittle and low-tensile chromium on the sample surface results in the formation of cracks in it under loading. The cracks are concentrators of strains, i.e. in the presence of chromium the work of crack initiation decreases. Therefore, mechanical characteristics of samples with chromium on the surface turn out to be lower than those in the chromium absence. Hydrogen accumulation in the steel base reduces the work of crack propagation the greater the lower hydrogen content is. Hence, mechanical characteristics of chrome-plated samples have the least magnitude at the highest hydrogen content in the steel base

  15. Propuesta para la recuperación de los machetes Zuazaga de los centrales azucareros con electrodos de acero al cromo. // Proposal for Recuperation of Sugar Mill Cut Cane by Using Chromium Steel Electrodes.

    Directory of Open Access Journals (Sweden)

    R. Collazo-Carceller

    2009-09-01

    Full Text Available El trabajo resume el estudio y análisis desarrollado, para la presentación de una propuestatecnológica de recuperación de los machetes Zuazaga, en nuestros centrales azucareros. Sedeterminó la influencia de los parámetros, energía introducida (Hi, número de capas (Nc y anchodel depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo, utilizandoel electrodo de acero al cromo DUR 600. Se realizó una valoración económica de la propuestatecnológica.Palabras claves: morfología, desgaste abrasivo, parámetro de soldadura, dendrites._____________________________________________________________________________AbstractThis work, sumarises the study and the analisys developed, to prupose the Zuazaga cut canethecnology recuperation, in aur sugar mills. The parameters influency was determinated, Heatinput (Hi, Number of layers (Nc and the Cord whith (Ad, in the mofology and the abrasive wearresistance increase, using the cromiun steel UTP DUR - 600. The economical calculation of thethecnology was done.Key words: morphology abrasive wear, welding parameters. dendrites, modeling

  16. Microstructure and properties of laser surface alloyed PM austenitic stainless steel

    OpenAIRE

    Z. Brytan; M. Bonek; L.A. Dobrzański

    2010-01-01

    Purpose: The purpose of this paper is to analyse the effect of laser surface alloying with chromium on the microstructural changes and properties of vacuum sintered austenitic stainless steel type AISI 316L (EN 1.4404).Design/methodology/approach: Surface modification of AISI 316L sintered austenitic stainless steel was carried out by laser surface alloying with chromium powder using high power diode laser (HPDL). The influence of laser alloying conditions, both laser beam power (between 0.7 ...

  17. Trivalent chromium sorption on alginate beads

    OpenAIRE

    Araújo, M. Manuela; Teixeira, J.A.

    1997-01-01

    The applicability of trivalent chromium removal from aqueous solutions using calcium alginate beads was studied. The equilibrium isotherms were plotted at two temperatures. The relationship between the chromium sorbed and the calcium released was determined as well as the effect of alginate amount and initial pH on the equilibrium results. Chromium sorption kinetics were evaluated as a function of chromium initial concentration and temperature. Transport properties of trival...

  18. Reduction of Late In-Stent Stenosis in a Porcine Coronary Artery Model by Cobalt Chromium Stents with a Nanocoat of Polyphosphazene (Polyzene-F)

    International Nuclear Information System (INIS)

    The purpose of this study was to investigate the potential of nanoscale coating with the highly biocompatible polymer Polyzene-F (PZF), in combination with cobalt chromium and stainless steel stents, to reduce in-stent stenosis, thrombogenicity, and vessel wall injury and inflammation. One bare cobalt chromium, PZF-nanocoated stainless steel or PZF-nanocoated cobalt chromium stent was implanted in right coronary artery of 30 mini-pigs (4- or 12-week follow-up). Primary study end points were in-stent stenosis and thrombogenicity. Secondary study end points were vessel wall injury and inflammation as evaluated by microscopy and a new immunoreactivity score applying C-reactive protein (CRP), tumor-necrosis factor alpha (TNFα), and TGFβ. At 12 weeks, angiography showed a significantly lower average loss in lumen diameter (2.1% ± 3.05%) in PZF-nanocoated cobalt chromium stents compared with stents in the other groups (9.73% ± 4.93% for bare cobalt chromium stents and 9.71% ± 7% for PZF-nanocoated stainless steel stents; p = 0.04), which was confirmed at microscopy (neointima 40.7 ± 16 μm in PZF-nanocoated cobalt chromium stents, 74.7 ± 57.6 μm in bare cobalt chromium stents, and 141.5 ± 109 μm in PZF-nanocoated stainless steel stents; p = 0.04). Injury and inflammation scores were low in all stents and were without significant differences. PZF-nanocoated cobalt chromium stents provided the highest efficacy in reducing in-stent stenosis at long-term follow-up. The PZF nanocoat proved to be biocompatible with respect to thromboresistance and inflammation. Our data suggest that its combination with cobalt chromium stents might provide an interesting passive stent platform.

  19. Estudio del comportamiento de los recargues multicapas de depósitos soldados de fundición blanca al cromo // Study of the hard facing weld behavior in deposits of white chromium steels.

    Directory of Open Access Journals (Sweden)

    R. Collazo-Carceller

    2009-05-01

    Full Text Available Se determina la influencia de los parámetros Energía introducida (Hi, Número de capas (Nc yAncho del depósito (Ad, en la morfología y el incremento de la resistencia al desgaste abrasivo decapas depositadas sobre acero 1020 utilizando el electrodo de fundición blanca al cromo UTPLedurit – 61. Empleando la microscopia óptica se identificaron y cuantificaron las fases presentes,analizando su efecto en el desgaste. Siendo determinante la influencia de la inclinación de lasdendritas y su posición con respecto a 90° en el incremento de la resistencia al desgaste abrasivo.Se caracterizaron los posibles mecanismos de daño superficial provocado por desgaste abrasivoempleando la microscopia electrónica de barrido. Se propusieron modelos lineales paracorrelacionar la influencia de la cantidad, tamaño, dispersión de los carburos y el ángulo deinclinación de las dendritas, en el incremento de la resistencia al desgaste.Palabras claves: morfología, desgaste abrasivo, parámetros de soldadura, dendritas, modelos.__________________________________________________________________________AbstractThe influence of different parameters in layer morphology and abrasion resistance of Fe-Cr-Celectrodes UTP Ledurit – 61 on steel 1020 was studied. Introduced Energy (Hi, Number of Layers(Nc, and Deposit Width (Ad were the main parameters considered. The metallographicidentification and quantification of metal phases and the determination of their effect in abrasionresistance were made with optical microscopy. The abrasive wear test characterized by scanningelectron microscopy, defines a possible mechanism of surface damage. It was found that the angleformed between a normal line to the surface and the dendrite inclination is directly related withthe increment of wear resistance. Lineal models that correlate wear resistance with quantity, size,and carbide dispersion and dendrite angle inclination were also developed.Key words: morphology, abrasive

  20. On texture formation of chromium electrodeposits

    DEFF Research Database (Denmark)

    Nielsen, Christian Bergenstof; Leisner, Peter; Horsewell, Andy

    1998-01-01

    The microstructure, texture and hardness of electrodeposited hard, direct current (DC) chromium and pulsed reversed chromium has been investigated. These investigations suggest that the growth and texture of hard chromium is controlled by inhibition processes and reactions. Further, it has been...

  1. Chromium Salen Mediated Alkene Epoxidation

    DEFF Research Database (Denmark)

    Petersen, Kaare Brandt; Norrby, Per-Ola; Daly, Adrian M.; Gilheany, Declan G.

    2002-01-01

    The mechanism of alkene epoxidation by chromium(v) oxo salen complexes has been studied by DFT and experimental methods. The reaction is compared to the closely related Mn-catalyzed process in an attempt to understand the dramatic difference in selectivity between the two systems. Overall, the......-spin surface. The low-spin addition of metal oxo species to an alkene leads to an intermediate which forms epoxide either with a barrier on the low-spin surface or without a barrier after spin inversion. Supporting evidence for this intermediate was obtained by using vinylcyclopropane traps. The chromium...

  2. Chromium content of selected Greek foods.

    Science.gov (United States)

    Bratakos, Michael S; Lazos, Evangelos S; Bratakos, Sotirios M

    2002-05-01

    The total chromium content of a wide variety of Greek foods was determined by graphite furnace atomic absorption spectroscopy (GFAAS). Meat, fish and seafood, cereals and pulses were rich sources of chromium (>0.100 microg/g). Fruits, milk, oils and fats and sugar were poor sources. Differences in chromium content were found between different food classes from Greece and those from some other countries. Based on available food consumption data and chromium levels in this study, it was estimated that the chromium intake of Greeks is 143 microg/day, with vegetables, cereals and meat being the main contributors. PMID:12083715

  3. Heat treatment and effects of Cr and Ni in low alloy steel

    Indian Academy of Sciences (India)

    Mohammad Abdur Razzak

    2011-12-01

    The effects of Cr and Ni on low carbon steel was observed. Undissolved carbide particles refine the austenite grain size. In the presence of nickel, chromium carbide is less effective in austenite grain refinement than chromium carbide in absence of nickel at temperature below 975°C. Nickel does not produce any austenite grain refinement but presence of nickel promotes the formation of acicular ferrites. It was also found that Ni and Cr as chromium carbide also refines the ferrite grain size and morphology. Cr as chromium carbide is more effective in refining ferrite grain size than nickel.

  4. Laser transformation hardening of a high-purity iron-carbon-chromium alloy

    International Nuclear Information System (INIS)

    Successful laser transformation hardening of steel surfaces requires that the absorbed laser energy is sufficient to austenitize the initial microstructure to a depth of 0.5 mm or more. Hardening is accomplished when rapid cooling by conduction of heat away from the surface causes transformation of the austenite layer to martensite. Heating and cooling rates of 104 K/s or greater are typical of the laser hardening process and the entire thermal cycle may be accomplished in less than 0.1 s. In an earlier study, laser surface hardening of commercial plain carbon and chromium alloyed steels was examined. It was shown that in the alloyed steel chromium enrichment of the cementite in the initial microstructure could prevent complete transformation of pearlite to asutenite during the very rapid laser heating cycle. However, interpretation of the results was complicated somewhat by the fact that manganese was also partitioned to the cementite. The purpose of this work was to conduct selected identical laser heating experiments on a high-purity Fe-C-Cr alloy to test the effect of chromium unequivocally, i.e., in the absence of manganese and other elements normally present in commercial steels

  5. On the chemical nature of boundary lubrication of stainless steel by chlorine - and sulfur-containing EP-additives

    DEFF Research Database (Denmark)

    Petrushina, Irina; Christensen, Erik; Bergqvist, Rene Stig; Møller, Poul Bildsøe; Bjerrum, Niels; Høj, Jakob Weiland; Kann, G.; Chorkendorff, Ib

    paraffin was equally active with iron, chromium and nickel. The better lubrication performance demonstrated by chlorinated paraffin compared to dialkylpolysulfides was attributed to the chemical activity of the chlorinated paraffin with all the main components of stainless steel. The depth profiles of the...... the Me-powder (where Me = iron, chromium or nickel)-dialkylpolysulfide (or chlorinated paraffin) mixtures have shown that dialkylpolysulfide was chemically active with iron and nickel (the highest activity was with nickel). Chromium was practically nonactive with dialkylpolysulfide. Chlorinated...

  6. Determination of chromium combined with DNA, RNA and protein in chromium-rich brewer's yeast

    International Nuclear Information System (INIS)

    The contents of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast were determined with the neutron activation analysis in order to study the combination of Cr with DNA, RNA and protein in chromium-rich brewer's yeast. The results showed that the extracting rats and concentrations of DNA, RNA and protein had no significant difference in two types of yeast, but the chromium contents of DNA, RNA and protein in the chromium-rich yeast were significantly higher than those in the normal. In addition, the content of chromium in DNA was much higher than that in RNA and protein, which indicated that the inorganic chromium compounds entered into the yeast cell, during the yeast cultivation in the culture medium containing chromium were converted into organic chromium compounds combined with DNA, RNA and protein

  7. The behaviour of chromium in aquatic and terrestrial food chains

    International Nuclear Information System (INIS)

    Chromium has been considered both as potential radioactive and conventional pollutant. Chromium-51 is produced by the activation of 50Cr, which may be present either as a component of steel alloys used in reactors, or in Na2CrO4 added as an anticorrosion agent to the cooling water. Only small amounts of 51Cr are normally found in the liquid waste of nuclear power plants before discharge into rivers. In exceptional situations, however, as a result of the direct release of cooling waters, the aquatic environments may receive relatively large quantities of 51Cr. Part of this 51Cr is adsorbed e.g. to the sediments, but a fraction remains in solution in the river water. Somme accumulation of the radionuclide is observed in fresh water and marine organisms. Therefore, although 51Cr has a relatively short physical half life (27.8d), it is of interest to acquire better information on its accumulation by different species of fresh water organisms and plants, as well as on its behaviour in soils, in order to evaluate the relative importance of this nuclide in the radioactive contamination of the aquatic and terrestrial food chains. As a related and sometimes associated pollutant, stable chromium is also taken into consideration. This element occurs fairly frequently as an environmental pollutant in many countries, either because of its abundance in soils derived from serpentine or because of its release to the environment from industrial wastes. The sequence of presentation of the experiment data is based on the consecutive steps of the contamination process: aquatic environment, soils, plant link of the food chain. Special attention is paid, in the different chapters, to the behaviour of various chemical forms of chromium and to their distribution in different fractions: soluble in water, adsorbed, precipitated on particles or complexed with organic material

  8. A comparison of the iraddiated tensile properties of a high-manganese austenitic steel and type 316 stainless steel

    International Nuclear Information System (INIS)

    The USSR steel EP-838 is a high-manganese, low-nickel steel that also has lower chromium and molybdenum than type 316 stainless steel. Tensile specimens of 20%-cold-worked EP-838 and type 316 stainless steel were irradiated in the High Flux Isotope Reactor (HFIR) at the coolant temperature (approx.=500C). A displacement damage level of 5.2 dpa was reached for the EP-838 and up to 9.5 dpa for the type 316 stainless steel. Tensile tests at room temperature and 3000C on the two steels indicated that the irradiation led to increased strength and decreased ductility compared to the unirradiated steels. Although the 0.2% yield stress of the type 316 stainless steel in the unirradiated condition was greater than that for the EP-838, after irradiation there was essentially no difference between the strength or ductility of the two steels. The results indicate that the replacement of the majority of the nickel by manganese and a reduction of chromium and molybdenum in an austenitic stainless steel of composition near that for type 316 stainless steel has little effect on the irradiated and unirradiated tensile properties at low temperatures. (orig.)

  9. Comparison of the irradiated tensile properties of a high-manganese austenitic steel and type 16 stainless steel

    International Nuclear Information System (INIS)

    The USSR steel EP-838 is a high-manganese (13.5%), low-nickel (4.2%) steel that also has lower chromium and molybdenum than type 316 stainless steel. Tensile specimens of 20%-cold-worked EP-838 and type 316 stainless steel were irradiated in the High Flux Isotope Reactor (HFIR) at the coolant temperature (approx. 500C). A displacement damage level of 5.2 dpa was reached for the EP-838 and up to 9.5 dpa for the type 316 stainless steel. Tensile tests at room temperature and 3000C on the two steels indicated that the irradiation led to increased strength and decreased ductility compared to the unirradiated steels. Although the 0.2% yield stress of the type 316 stainless steel in the unirradiated condition was greater than that for the EP-838, after irradiation there was essentially no difference between the strength or ductility of the two steels. The results indicate that the replacement of the majority of the nickel by manganese and a reduction of chromium and molybdenum in an austenitic stainless steel of composition near that for type 316 stainless steel has little effect on the irradiated and unirradiated tensile properties at low temperatures

  10. Synthesis of chromium and ferrochromium alloy in molten salts by the electro-reduction method

    Directory of Open Access Journals (Sweden)

    Ge X.

    2015-01-01

    Full Text Available In this work, we successfully applied the Fray-Farthing-Chen Cambridge electro-reduction process on the preparation of chromium from chromium oxide, and for the first time, the synthesis of ferrochromium alloy from chromium oxide and iron oxide mixture and the chromite ore in molten calcium chloride. The present work systematically investigated the influences of sintered temperature of the solid precursor, electrochemical potential, electrolysis temperature and time on the products by using a set of advanced characterization techniques, including XRD and SEM/EDS analyses. In particular, our results show that this process is energy-friendly and technically-feasible for the direct extraction of ferrochromium alloy from chromite ore. Our findings thus provide useful insights for designing a novel green process to produce ferrochromium alloy from low-grade chromite ore or stainless steel slag.

  11. Analysis of the structure of castings made from chromium white cast iron resistant to abrasive wear

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-10-01

    Full Text Available It has been proved that an addition of boron carbide and disintegrated steel scrap introduced as an inoculant to the chromium white cast iron changes the structure of castings. The said operation increases the number of crystallization nuclei for dendrites of the primary austenite. In this case, the iron particles act as substrates for the nucleation of primary austenite due to a similar crystallographic lattice. The more numerous are the dendrites of primary austenite and the structure more refined and the mechanical properties higher. Castings after B4C inoculation revealed a different structure of fine grained fracture. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  12. Experimental and Theoretical Investigations of Hot Isostatically Pressed-Produced Stainless Steel/High Alloy Tool Steel Compound Materials

    Science.gov (United States)

    Lindwall, Greta; Flyg, Jesper; Frisk, Karin; Sandberg, Odd

    2011-05-01

    Consolidation of tool steel powders and simultaneous joining to a stainless 316L steel are performed by hot isostatic pressing (HIP). Two tool steel grades are considered: a high vanadium alloyed carbon tool steel, and a high vanadium and chromium alloyed nitrogen tool steel. The boundary layer arising during diffusion bonding is in focus and, in particular, the diffusion of carbon and nitrogen over the joint. Measurements of the elemental concentration profiles and corrosion tests by the double loop-electrochemical potentiokinetic reactivation (DL-EPR) method are performed. Comparative calculations with the DICTRA software are performed and are found to be in agreement with the experimental results. It is found that the carbon tool steel grade has a more critical influence on the corrosion resistance of the stainless 316L steel in comparison to the nitrogen tool steel grade.

  13. Corrosion behavior of HVOF-sprayed and Nd-YAG laser-remelted high-chromium, nickel-chromium coatings

    Science.gov (United States)

    Tuominen, J.; Vuoristo, P.; Mäntylä, T.; Ahmaniemi, S.; Vihinen, J.; Andersson, P. H.

    2002-06-01

    Thermal spray processes are widely used to deposit high-chromium, nickel-chromium coatings to improve high temperature oxidation and corrosion behavior. However, despite the efforts made to improve the present spraying techniques, such as high-velocity oxyfuel (HVOF) and plasma spraying, these coatings may still exhibit certain defects, such as unmelted particles, oxide layers at splat boundaries, porosity, and cracks, which are detrimental to corrosion performance in severe operating conditions. Because of the process temperature, only mechanical bonding is obtained between the coating and substrate. Laser remelting of the sprayed coatings was studied in order to overcome the drawbacks of sprayed structures and to markedly improve the coating properties. The coating material was high-chromium, nickel-chromium alloy, which contains small amounts of molybdenum and boron (53.3% Cr, 42.5% Ni, 2.5% Mo, 0.5% B). The coatings were prepared by HVOF spraying onto mild steel substrates. A high-power, fiber-coupled, continuous-wave Nd:YAG laser equipped with large beam optics was used to remelt the HVOF-sprayed coating using different levels of scanning speed and beam width (10 or 20 mm). Coating that was remelted with the highest traverse speed suffered from cracking because of the rapid solidification inherent to laser processing. However, after the appropriate laser parameters were chosen, nonporous, crack-free coatings with minimal dilution between coating and substrate were produced. Laser remelting resulted in the formation of a dense oxide layer on top of the coatings and full homogenization of the sprayed structure. The coatings as sprayed and after laser remelting were characterized by optical and electron microscopy (OM, SEM, respectively). Dilution between coating and substrate was studied with energy dispersive spectrometry (EDS). The properties of the laser-remelted coatings were directly compared with properties of as-sprayed HVOF coatings.

  14. Plant Line Trial Evaluation of Viable Non-Chromium Passivation Systems for Electrolytin Tinplate, ETP (TRP 9911)

    Energy Technology Data Exchange (ETDEWEB)

    John A. Sinsel

    2003-06-30

    Plant trial evaluations have been completed for two zirconium-based, non-chromium passivation systems previously identified as possible alternatives to cathodic dichromate (CDC) passivation for electrolytic tinplate (ETP). These trials were done on a commercial electrolytic tin plating line at Weirton Steel and extensive evaluations of the materials resulting from these trials have been completed. All this was accomplished as a collaborative effort under the AISI Technology Roadmap Program and was executed by seven North American Tin Mill Products producers [Bethlehem Steel (now acquired by International Steel Group (ISG)), Dofasco Inc., National Steel (now acquired by U.S. Steel), U.S. Steel, USS-Posco, Weirton Steel, and Wheeling-Pittsburgh Steel] with funding partially from the Department of Energy (DOE) and partially on an equal cost sharing basis among project participants. The initial phases of this project involved optimization of application procedures for the non-chromium systems in the laboratories at Bethlehem Steel and Betz Dearborn followed by extensive testing with various lacquer formulations and food simulants in the laboratories at Valspar and PPG. Work was also completed at Dofasco and Weirton Steel to develop methods to prevent precipitation of insoluble solids as a function of time from the zirconate system. The results of this testing indicated that sulfide staining characteristics for the non-chromium passivation systems could be minimized but not totally eliminated and neither system was found to perform quite as good, in this respect, as the standard CDC system. As for the stability of zirconate treatment, a method was developed to stabilize this system for a sufficient period of time to conduct plant trial evaluations but, working with a major supplier of zirconium orthosulfate, a method for long term stabilization is still under development.

  15. Austenitic stainless steels with cryogenic resistance

    International Nuclear Information System (INIS)

    The most used austenitic stainless steels are alloyed with chromium and nickel and have a reduced carbon content, usually lower than 0.1 % what ensures corresponding properties for processing by plastic deformation at welding, corrosion resistance in aggressive environment and toughness at low temperatures. Steels of this kind alloyed with manganese are also used to reduce the nickel content. By alloying with manganese which is a gammageneous element one ensures the stability of austenites. Being cheaper these steels may be used extensively for components and equipment used in cryogenics field. The best results were obtained with steels of second group, AMnNi, in which the designed chemical composition was achieved, i.e. the partial replacement of nickel by manganese ensured the toughness at cryogenic temperatures. If these steels are supplementary alloyed, their strength properties may increase to the detriment of plasticity and toughness, although the cryogenic character is preserved

  16. Tissues and urinary chromium concentrations in rats fed high-chromium diets

    International Nuclear Information System (INIS)

    Complete text of publication follows. Chromium is an essential trace elements and enhances the function of insulin as a form of chromodulin. In the subjects with a certain type of diabetics, 200 to 1,000 μg/d of chromium is administered to reduced the symptoms of diabetics. However, although there are not any health-promotive effects of chromium-administration in healthy subjects, various types of chromium supplements are commercially available in many countries; the adverse effects caused by an excessive chromium intake are feared. In the present study, to clarify the tolerable upper limit of chromium, tissue and urinary chromium concentrations, liver function and iron status were examined in rats fed high-chromium diets. Thirty-six male 4-weeks Wistar rats were divided into six groups and fed casein-based diets containing 1, 10 or 100 μg/g of chromium as chromium chloride (CrCl3) or chromium picolinate (CrPic) for 4 weeks. After the feeding, chromium concentrations in liver, kidney, small intestine and tibia were determined by inductively coupled plasma-mass spectrometry. In addition, urine samples were collected on 3rd to 4th week and their chromium concentrations were also determined. Chromium concentrations in liver, kidney, small intestine and tibia were elevated with increase of dietary chromium concentration. Urinary chromium excretion was also elevated with the increase of dietary chromium and the rate of urinary chromium excretion was less than 2% to dietary chromium intake in all the experimental groups. In the administration of 100 μg/g of chromium, rats given CrCl3 showed significantly higher tibia chromium concentration and lower urinary chromium excretion than those given CrPic. There were not any differences in iron status among the experimental groups. Activities of serum aspartate aminotransferase and alanine aminotransferase in rats fed diet containing 100 μg/g of chromium as CrPic were significantly higher than those in rats fed other diets.

  17. A fundamental study of chromium deposition on solid oxide fuel cell cathode materials

    Science.gov (United States)

    Tucker, Michael C.; Kurokawa, Hideto; Jacobson, Craig P.; De Jonghe, Lutgard C.; Visco, Steven J.

    Chromium contamination of metal oxides and SOFC cathode catalysts is studied in the range 700-1000 °C. Samples are exposed to a moist air atmosphere saturated with volatile Cr species in the presence and absence of direct contact between the sample and ferritic stainless steel powder. Chromium contamination of the samples is observed to occur via two separate pathways: surface diffusion from the stainless steel surface and vapor deposition from the atmosphere. Surface diffusion dominates in all cases. Surface diffusion is found to be a significant source of Cr contamination for LSM and LSCF at 700, 800, and 1000 °C. Vapor deposition of Cr onto LSCF was observed at each of these temperatures, but was not observed for LSM at 700 or 800 °C. Comparison of the behavior for LSM, LSCF, and single metal oxides suggests that Mn and Co, respectively, are responsible for the Cr contamination of these catalysts.

  18. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag

    International Nuclear Information System (INIS)

    Hexavalent chromium (Cr) is a toxic element causing serious environmental threat. Recently, more and more attention is paid to the bio-remediation of Cr (VI) in the contaminated soils. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag at a steel-alloy factory in Hunan Province, China, was investigated in the present study. The results showed that when sufficient nutrients were amended into the contaminated soils, total Cr (VI) concentration declined from the initial value of 462.8 to 10 mg kg-1 at 10 days and the removal rate was 97.8%. Water soluble Cr (VI) decreased from the initial concentration of 383.8 to 1.7 mg kg-1. Exchangeable Cr (VI) and carbonates-bound Cr (VI) were removed by 92.6% and 82.4%, respectively. Meanwhile, four Cr (VI) resistant bacterial strains were isolated from the soil under the chromium-containing slag. Only one strain showed a high ability for Cr (VI) reduction in liquid culture. This strain was identified as Pannonibacter phragmitetus sp. by gene sequencing of 16S rRNA. X-ray photoelectron spectroscope (XPS) analysis indicated that Cr (VI) was reduced into trivalent chromium. The results suggest that indigenous bacterial strains have potential application for Cr (VI) remediation in the soils contaminated by chromium-containing slag.

  19. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag.

    Science.gov (United States)

    Chai, Liyuan; Huang, Shunhong; Yang, Zhihui; Peng, Bing; Huang, Yan; Chen, Yuehui

    2009-08-15

    Hexavalent chromium (Cr) is a toxic element causing serious environmental threat. Recently, more and more attention is paid to the bio-remediation of Cr (VI) in the contaminated soils. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag at a steel-alloy factory in Hunan Province, China, was investigated in the present study. The results showed that when sufficient nutrients were amended into the contaminated soils, total Cr (VI) concentration declined from the initial value of 462.8 to 10 mg kg(-1) at 10 days and the removal rate was 97.8%. Water soluble Cr (VI) decreased from the initial concentration of 383.8 to 1.7 mg kg(-1). Exchangeable Cr (VI) and carbonates-bound Cr (VI) were removed by 92.6% and 82.4%, respectively. Meanwhile, four Cr (VI) resistant bacterial strains were isolated from the soil under the chromium-containing slag. Only one strain showed a high ability for Cr (VI) reduction in liquid culture. This strain was identified as Pannonibacter phragmitetus sp. by gene sequencing of 16S rRNA. X-ray photoelectron spectroscope (XPS) analysis indicated that Cr (VI) was reduced into trivalent chromium. The results suggest that indigenous bacterial strains have potential application for Cr (VI) remediation in the soils contaminated by chromium-containing slag. PMID:19246154

  20. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag

    Energy Technology Data Exchange (ETDEWEB)

    Chai Liyuan; Huang Shunhong [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Yang Zhihui, E-mail: yangzh@mail.csu.edu.cn [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China); Peng Bing; Huang Yan; Chen Yuehui [School of Metallurgical Science and Engineering, Central South University, Changsha 410083 (China)

    2009-08-15

    Hexavalent chromium (Cr) is a toxic element causing serious environmental threat. Recently, more and more attention is paid to the bio-remediation of Cr (VI) in the contaminated soils. Cr (VI) remediation by indigenous bacteria in soils contaminated by chromium-containing slag at a steel-alloy factory in Hunan Province, China, was investigated in the present study. The results showed that when sufficient nutrients were amended into the contaminated soils, total Cr (VI) concentration declined from the initial value of 462.8 to 10 mg kg{sup -1} at 10 days and the removal rate was 97.8%. Water soluble Cr (VI) decreased from the initial concentration of 383.8 to 1.7 mg kg{sup -1}. Exchangeable Cr (VI) and carbonates-bound Cr (VI) were removed by 92.6% and 82.4%, respectively. Meanwhile, four Cr (VI) resistant bacterial strains were isolated from the soil under the chromium-containing slag. Only one strain showed a high ability for Cr (VI) reduction in liquid culture. This strain was identified as Pannonibacter phragmitetus sp. by gene sequencing of 16S rRNA. X-ray photoelectron spectroscope (XPS) analysis indicated that Cr (VI) was reduced into trivalent chromium. The results suggest that indigenous bacterial strains have potential application for Cr (VI) remediation in the soils contaminated by chromium-containing slag.

  1. Food Chromium Contents, Chromium Dietary Intakes And Related Biological Variables In French Free-Living Elderly

    Science.gov (United States)

    Chromium (Cr III), an essential trace element, functions in potentiating insulin sensitivity, regulating glucose homeostasis, improving lipid profile, and maintaining lean body mass. Glucose intolerance and chromium deficiency increase with age, and could be aggravating factors of the metabolic synd...

  2. Soils contaminated with hexavalent chromium

    OpenAIRE

    Fonseca, Bruna Catarina da Silva

    2011-01-01

    Tese de doutoramento em Engenharia Química e Biológica The interest in environmental soil science has been growing in the last years due to the continuous degradation of this major natural resource. With this in mind, and because chromium and lead are two of the most toxic heavy metals frequently detected as soil contaminants in the Portuguese territory, the study and development of few remediation techniques and the indissociable description of the sorption and migration of...

  3. Carbon, chromium and molybdenum contents

    International Nuclear Information System (INIS)

    This work describes solidification experiments on white cast iron, with 15 and 20% of chromium, 2.3, 3.0 and 3.6 % of carbon and 0.0, 1.5 and 2.5 % of molybdenum in test de samples with 30 mm diameter. Measurements were performed on the austenite and eutectic formation arrests, the number of the eutectic carbide particles relative to the total and the eutectic volumes, and the volume fraction of the primary austenite

  4. A Comparative Study of Biodegradation of Nickel and Chromium from Space Maintainers: An in vitro Study

    OpenAIRE

    Anand, Ashish; Sharma, Arun; Kumar, Piush; Sandhu, Meera; Sachdeva, Shobhit; Sachdev, Vinod

    2015-01-01

    ABSTRACT Objective: The aim of the study was to compare and evaluate the in vitro biodegradation of nickel and chromium from space maintainers, made of three different companies, i.e (Dantaurum, Rocky mountain and Dtech) in artificial saliva. Materials and methods: The study comprised of 30 space maintainers out of which 10 were fabricated using Dantaurum, 10 using Rocky mountain and 10 using Dtech band materials. Stainless steel wire (Dantaurum, Rocky mountain and Konark) was used for making...

  5. Atom probe study of chromium oxide spinels formed during intergranular corrosion

    International Nuclear Information System (INIS)

    Atom probe microscopy has been used to study the inhomogeneous nature of chromium oxide spinels in intergranular corrosion of a 253 MA austenitic stainless steel after thermal cycling up to 970 °C in air. The results indicate that the non-continuous character of the spinel layers originates from nanoscale phases such as iron-rich oxides along the chromite grain boundaries and silicate particles. Their role in the rate of intergranular corrosion is discussed

  6. Preparation and Characterization of Nanocrystalline Hard Chromium Coatings Using Eco-Friendly Trivalent Chromium Bath

    OpenAIRE

    V. S. Protsenko; V. O Gordiienko; Danilov, F. I.; Kwon, S.C.

    2011-01-01

    A new aqueous sulfate trivalent chromium bath is described. The chromium bath contains formic acid and carbamide as complexing agents. Chromium was deposited at a temperature of 30÷40 oC and a cathode current density of 10÷25 A dm-2. The bath allows obtaining thick (up to several hundred micrometers) hard chromium coatings with nanocrystalline structure. The electrodeposition rate reaches 0.8÷0.9 µm min-1.

  7. REMOVAL OF HEXAVALENT CHROMIUM FROM DRINKING WATER

    OpenAIRE

    A. R. Asgari ، F. Vaezi ، S. Nasseri ، O. Dördelmann ، A. H. Mahvi ، E. Dehghani Fard

    2008-01-01

    Removal of chromium can be accomplished by various methods but none of them is cost-effective in meeting drinking water standards. For this study, granular ferric hydroxide was used as adsorbent for removal of hexavalent chromium. Besides, the effects of changing contact time, pH and concentrations of competitive anions were determined for different amounts of granular ferric hydroxide. It was found that granular ferric hydroxide has a high capacity for adsorption of hexavalent chromium from ...

  8. Inoculation of chromium white cast iron

    Directory of Open Access Journals (Sweden)

    D. Kopyciński

    2009-01-01

    Full Text Available It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  9. Inoculation of chromium white cast iron

    OpenAIRE

    D. Kopyciński

    2009-01-01

    It has been proved that an addition of boron carbide introduced as an inoculant to the chromium white cast iron changes the structureof castings. Castings after inoculation revealed a different structure with numerous grains. Primary precipitates of chromium carbide also appeared, reducing the mechanical properties of as-cast parts. Properly established heat treatment regime makes chromium iron castings regain their, originally high, mechanical properties.

  10. Male-mediated spontaneous abortion among spouses of stainless steel welders

    DEFF Research Database (Denmark)

    Hjollund, N H; Bonde, J P; Jensen, T K;

    2000-01-01

    Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among...... spouses of stainless-steel welders....

  11. Polypyrrole electrochemistry: Environmentally friendly corrosion protection of steel: (im)possibilities

    NARCIS (Netherlands)

    Hamer, W.J.

    2005-01-01

    Chromate compounds have been widely used to improve the corrosion protection of galvanised steel and aluminium objects in the past decades. The hexavalent chromium in chromate enhances the adherence of coatings to galvanised steel and aluminium. Additionally, if the passive layers on these material

  12. 75 FR 10207 - Certain Cut-to-Length Carbon-Quality Steel Plate From the Republic of Korea: Final Results of...

    Science.gov (United States)

    2010-03-05

    .... Also, specifically included in the scope of the order are high strength, low alloy (HSLA) steels. HSLA steels are recognized as steels with micro-alloying levels of elements such as chromium, copper, niobium... Review and Intent To Rescind Administrative Review in Part, 74 FR 48716 (September 24, 2009),...

  13. 77 FR 264 - Certain Cut-To-Length Carbon-Quality Steel Plate From India, Indonesia, and the Republic of Korea...

    Science.gov (United States)

    2012-01-04

    ... within the scope. Also, specifically included in the scope are high strength, low alloy (``HSLA'') steels. HSLA steels are recognized as steels with micro- alloying levels of elements such as chromium, copper... ``Act''), respectively. See Initiation of Five-Year (``Sunset'') Review, 75 FR 67082 (November 1,...

  14. Assessing resistance of stabilized corrosion resistant steels to intergranular corrosion

    International Nuclear Information System (INIS)

    Resistance to intergranular corrosion was determined for four types of titanium-stabilized steels from the coefficients of stabilization efficiency according to the degree the chemical composition was known. The ATA SUPER steel showed the highest resistance parameter value. The resistance of this type of steel of a specific composition, showing a relatively low value of mean nitrogen content was compared with steel of an optimized chemical composition and with low-carbon niobium stabilized, molybdenum modified steels. The comparison showed guarantees of a sufficient resistance of the steel to intergranular corrosion. The method of assessing the resistance to intergranular corrosion using the calculation of the minimum content of Cr', i.e., the effective chromium content, and the maximum effective carbon content C' giving the resistance parameter k seems to be prospective for practical use in the production of corrosion resistant steels. (author). 1 tab., 5 figs., 15 refs

  15. Permeation of chromium salts through human skin in vitro

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Fullerton, A; Avnstorp, C;

    1992-01-01

    of the dichromate solution. Chromium skin levels increased with increasing concentrations of applied chromium salts up to 0.034 M Cr. The amount of chromium in recipient phase and skin layers increased with increasing pH when the applied solution contained potassium dichromate. This was ascribed to a decreased skin...... barrier function of the skin. The amount of chromium found in all skin layers after application of chromium chloride decreased with increasing pH due to lower solubility of the salt. The % of chromium found in the recipient phase as chromium(VI) increased with increasing total chromium concentration...... indicating a limited reduction ability of the skin in vitro....

  16. Microstructure and impact response of high-chromium ODS steels

    Czech Academy of Sciences Publication Activity Database

    Hadraba, Hynek; Fournier, B.; Stratil, Luděk; Dlouhý, Ivo

    Ostrava: VŠB - TU Ostrava, 2010 - (Strnadel, B.), s. 145-151 ISBN 978-80-248-2265-5. [New Methods of Damage and Failure Analysis of Structural Parts. Ostrava (CZ), 06.09.2010-10.09.2010] R&D Projects: GA ČR GA106/08/1397 Institutional research plan: CEZ:AV0Z20410507 Keywords : thermal ageing * brittleness * fracture Subject RIV: JG - Metallurgy

  17. Corrosion-chemical studies on the austenitic CrNi steel 1.4306 using the radioisotope method

    International Nuclear Information System (INIS)

    The aim of the present study was to investigate into the corrosion behaviour of the austenitic chromium-nickel-steel 1.4306 N in hydrous purex solutions. The radioisotope method and electrochemical processes were applied as methods of investigation. The neutron activation of steel required for the application of RIM permits the γ-spectroscopic detection of the three main constituents iron, chromium and nickel, under appropriate irradiation conditions. The iron was detected via the Fe-59 isotope, chromium via Cr-51, and nickel via Co-58. (orig./MM)

  18. Purity of food cooked in stainless steel utensils.

    Science.gov (United States)

    Flint, G N; Packirisamy, S

    1997-01-01

    An extensive programme of cooking operations, using household recipes, has shown that, apart from aberrant values associated with new pans on first use, the contribution made by 19% Cr/9% Ni stainless steel cooking utensils to chromium and nickel in the diet is negligible. New pans, if first used with acid fruits, showed a greater pick-up of chromium and nickel, ranging from approximately 1/20 to 1/3 and 1/20 to 1/2 of the normal daily intake of chromium and nickel respectively. This situation did not recur in subsequent usage, even after the pan had been cleaned by abrasion. A higher rate of chromium and nickel release in new pans on first use was observed on products from four manufactures and appears to be related to surface finish, since treatment of the surface of a new pan was partly, and in the case of electropolishing, wholly effective in eliminating their initial high release. PMID:9102344

  19. Pitting corrosion resistant austenite stainless steel

    Science.gov (United States)

    van Rooyen, D.; Bandy, R.

    A pitting corrosion resistant austenite stainless steel comprises 17 to 28 wt. % chromium, 15 to 26 wt. % nickel, 5 to 8 wt. % molybdenum, and 0.3 to 0.5 wt. % nitrogen, the balance being iron, unavoidable impurities, minor additions made in the normal course of melting and casting alloys of this type, and may optionally include up to 10 wt. % of manganese, up to 5 wt. % of silicon, and up to 0.08 wt. % of carbon.

  20. Spatial distribution of crystalline corrosion products formed during corrosion of stainless steel in concrete

    KAUST Repository

    Serdar, Marijana

    2015-05-01

    © 2015 Elsevier Ltd All rights reserved. The mineralogy and spatial distribution of nano-crystalline corrosion products that form in the steel/concrete interface were characterized using synchrotron X-ray micro-diffraction (μ-XRD). Two types of low-nickel high-chromium reinforcing steels embedded into mortar and exposed to NaCl solution were investigated. Corrosion in the samples was confirmed by electrochemical impedance spectroscopy (EIS). μ-XRD revealed that goethite (α-FeOOH) and akaganeite (β-FeOOH) are the main iron oxide-hydroxides formed during the chloride-induced corrosion of stainless steel in concrete. Goethite is formed closer to the surface of the steel due to the presence of chromium in the steel, while akaganeite is formed further away from the surface due to the presence of chloride ions. Detailed microstructural analysis is shown and discussed on one sample of each type of steel.

  1. Investigation of the corrosion fatigue behaviour of turbineblade steels in the region of initial steam condensation

    International Nuclear Information System (INIS)

    The fact that a large proportion of the total number of turbine failures is due to blade damage, particularly in the region of initial steam condensation, led to comprehensive investigations of the behaviour of 12/13% chromium steels. 17% Cr-4% Ni steel, duplex stainless steels and titanium alloys with regard to pitting corrosion and corrosion fatigue. The corrosion fatigue strength of these materials after a specific number of cycles in media representative of operating conditions is dependent principially on whether or not pitting corrosion and/or hydrogen-induced crack propagation along cleavage planes occur during dynamic loading in the relevant environment. With optimisation of heat treatment, duplex stainless steels free from copper, 17% Cr-4% Ni steel and the titanium alloy, TiAl6V4 offer better corrosion fatigue behaviour than the 12/13% chromium steels, performance improving in the order as listed. (orig.)

  2. Alkane dehydrogenation over supported chromium oxide catalysts

    NARCIS (Netherlands)

    Weckhuysen, B.M.; Schoonheydt, R.A.

    1999-01-01

    The dehydrogenation of alkanes over supported chromium oxide catalysts in the absence of oxygen is of high interest for the industrial production of propene and isobutene. In this review, a critical overview is given of the current knowledge nowadays available about chromium-based dehydrogenation ca

  3. Accelerated corrosion of stainless steel in thiocyanate-containing solutions

    Energy Technology Data Exchange (ETDEWEB)

    Pistorius, P Chris; Li, Wen

    2012-09-19

    It is known that reduced sulfur compounds (such as thiocyanate and thiosulfate) can accelerate active corrosion of austenitic stainless steel in acid solutions, but before we started this project the mechanism of acceleration was largely unclear. This work combined electrochemical measurements and analysis using scanning electron microscopy (SEM) and X-ray photo-electron spectroscopy (XPS), which provided a comprehensive understanding of the catalytic effect of reduced sulfur species on the active corrosion of stainless steel. Both the behavior of the pure elements and the steel were studied and the work focused on the interaction between the pure elements of the steel, which is the least understood area. Upon completion of this work, several aspects are now much clearer. The main results from this work can be summarized as follows: The presence of low concentrations (around 0.1 mM) of thiocyanate or tetrathionate in dilute sulfuric acid greatly accelerates the anodic dissolution of chromium and nickel, but has an even stronger effect on stainless steels (iron-chromium-nickel alloys). Electrochemical measurements and surface analyses are in agreement with the suggestion that accelerated dissolution really results from suppressed passivation. Even well below the passivation potential, the electrochemical signature of passivation is evident in the electrode impedance; the electrode impedance shows clearly that this pre-passivation is suppressed in the presence of thiocyanate. For the stainless steels, remarkable changes in the morphology of the corroded metal surface and in the surface concentration of chromium support the suggestion that pre-passivation of stainless steels is suppressed because dissolution of chromium is accelerated. Surface analysis confirmed that adsorbed sulfur / sulfide forms on the metal surfaces upon exposure to solutions containing thiocyanate or thiosulfate. For pure nickel, and steels containing nickel (and residual copper), bulk sulfide

  4. Recent advances in creep-resistant steels for power plant applications

    Indian Academy of Sciences (India)

    P J Ennis; A Czyrska-Filemonowicz

    2003-06-01

    The higher steam temperatures and pressures required to achieve increase in thermal efficiency of fossil fuel-fired power-generation plants necessitate the use of steels with improved creep rupture strength. The 9% chromium steels developed during the last three decades are of great interest in such applications. In this report, the development of steels P91, P92 and E911 is described. It is shown that the martensitic transformation in these three steels produces high dislocation density that confers significant transient hardening. However, the dislocation density decreases during exposure at service temperatures due to recovery effects and for long-term creep strength the sub-grain structure produced under different conditions is most important. The changes in the microstructure mean that great care is needed in the extrapolation of experimental data to obtain design values. Only data from tests with rupture times above 3,000 h provide reasonable extrapolated values. It is further shown that for the 9% chromium steels, oxidation resistance in steam is not sufficiently high for their use as thin-walled components at temperatures of 600°C and above. The potential for the development of steels of higher chromium contents (above 11%) to give an improvement in steam oxidation resistance whilst maintaining creep resistance to the 9% chromium steels is discussed.

  5. MORPHOLOGY MODIFICATION OF CARBON CHROME MOLYBDENUM STEEL STRUCTURE INFLUENCED BY HEAT TREATMENT

    Directory of Open Access Journals (Sweden)

    V. A. Lutsenko

    2011-01-01

    Full Text Available The influence of temperature and time parameters of thermal treatment on structural change and properties of carbon chromium molybdenum steel has been studied. It has been shown that there are considerable areas with grainy morphology of cementite after high temperature tempering in the structure of steel. It assures reduction of steel microhardness by 25%, and there are no substantial structural changes after medium temperature tempering.

  6. MORPHOLOGY MODIFICATION OF CARBON CHROME MOLYBDENUM STEEL STRUCTURE INFLUENCEDBY HEAT TREATMENT

    OpenAIRE

    Lutsenko, V.; Anelkin, N.; Golubenko, T.; Scherbakov, V.; Lutsenko, O.

    2011-01-01

    The influence of temperature and time parameters of thermal treatment on structural change and properties of carbon chromium molybdenum steel has been studied. It has been shown that there are considerable areas with grainy morphology of cementite after high temperature tempering in the structure of steel. It assures reduction of steel microhardness by 25%, and there are no substantial structural changes after medium temperature tempering.

  7. Morphology modification of carbon chrome molybdenum steel structure influenced by heat treatment

    OpenAIRE

    V. A. Lutsenko; N. L. Anelkin; T. N. Golubenko; Scherbakov, V. I.; O. V. Lutsenko

    2011-01-01

    The influence of temperature and time parameters of thermal treatment on structural change and properties of carbon chromium molybdenum steel has been studied. It has been shown that there are considerable areas with grainy morphology of cementite after high temperature tempering in the structure of steel. It assures reduction of steel microhardness by 25%, and there are no substantial structural changes after medium temperature tempering.

  8. Effect of heat treatment on mechanical properties of H11 tool steel

    OpenAIRE

    S.Z. Qamar

    2009-01-01

    Purpose: AISI H11 is a special alloy steel, categorized as chromium tool steel. Because of its high toughness and hardness, it is well suited for hot work applications involving very high loads. Typical applications are hot-work forging and extrusion dies, helicopter rotor blades, etc. For longer life and higher design accuracy, properties of this type of tool steel can be improved by various types of heat treatment. Current work reports and analyzes results of mechanical testing performed on...

  9. Exposure to stainless steel welding fumes and lung cancer: a meta-analysis.

    OpenAIRE

    Sjögren, B; Hansen, K S; Kjuus, H; Persson, P G

    1994-01-01

    Stainless steel welding is associated with exposure to metals including hexavalent chromium and nickel. This study is a meta-analysis of five studies of stainless steel welders and the occurrence of lung cancer. Asbestos exposure and smoking habits have been taken into account. The calculated pooled relative risk estimate was 1.94 with a 95% confidence interval of 1.28-2.93. This result suggests a causal relation between exposure to stainless steel welding and lung cancer.

  10. Radiation-induced grain boundary segregation effect on stress corrosion cracking in steel

    International Nuclear Information System (INIS)

    Stress corrosion cracking of stainless steels 304L, 316 and 316L irradiated at 673 K up to the dose of 0.8 dpa is studied. It is shown that radiation-induced reduction of chromium content in the grain boundary results in corrosion cracking of the steels in water containing dissolved oxygen. Corrosion cracking in water with dissolved hydrogen occurs in the context of radiation-induced strengthening of the steel and change in its microstructure

  11. Electrochemical reduction of hexavalent chromium in ground water

    Energy Technology Data Exchange (ETDEWEB)

    Bansal, S. [Lawrence Livermore National Lab., CA (United States)

    1994-12-01

    Electrochemical reduction of hexavalent chromium (Cr{sup +6}) to its trivalent state (Cr{sup +3}) is showing promising results in treating ground water at Lawrence Livermore National Laboratory`s (LLNL`s) Main Site. An electrolytic cell using stainless-steel and brass electrodes has been found to offer the most efficient reduction while yielding the least amount of precipitate. Trials have successfully lowered concentrations of Cr{sup +6} to below 11 parts per billion (micrograms/liter), the California state standard. We ran several trials to determine optimal voltage for running the cell; each trial consisted of applying a voltage between 6V and 48V for ten minutes through samples obtained at Treatment Facility C(TFC). No conclusive data has been obtained yet.

  12. Improvement of resistance to oxidation by laser alloying on a tool steel

    Energy Technology Data Exchange (ETDEWEB)

    Gemellli, E.; Gallerie, A.; Caillet, M.

    1998-10-13

    The goal of this work is to improve the resistance to oxidation at high temperature of a tool steel (D2) without degrading its satisfactory tribologic properties. In a recent paper, the authors showed that the combination in the same coating, of chromium and silicon can provide increased resistance to oxidation at high temperature, a combination which until then had been used only in massive alloys. The present investigation deals with a steel initially having 12% chromium. The addition of silicon to the steel surface should improve the resistance to oxidation to the minimum levels required by the steel high operating temperatures. On the other hand, it has also been shown that the chromium and carbon addition leads to the formation o hard phases [(Fe,Cr){sub 7}C{sub 3}] necessary for a good anti-wear behavior. The increase of the chromium concentration in solid solution and the presence of carbide in the coating, obtained by the addition of Cr{sub 3}C{sub 2}, should then increase not only the resistance to oxidation, but also the resistance to wear. The possibility of obtaining the same effects by the addition o silicon carbide or chromium carbide to the D2 steel surface has also been investigated.

  13. Neutron scattering and models: Chromium

    International Nuclear Information System (INIS)

    Differential neutron elastic-scattering cross sections of elemental chromium are measured from 4.5 ∼ 10 MeV in steps of ∼ 0.5 MeV and at ≥ 40 scattering angles distributed between ∼ 17 degree--160 degree. Concurrently differential cross sections for the inelastic neutron excitation of the yrast 2+ (1.434 MeV) level in d52Cr are determined. In addition, broad inelastically-scattered neutron groups are observed corresponding to composite excitation of levels up to ∼ 5.5 MeV in the various chromium isotopes. These experimental results are combined with low-energy values previously reported from this laboratory, with recent ∼ 8 → 15 MeV data measured at the Physikalisch-Technische Bundesanstalt and with a 21.6 MeV result from the literature to form an extensive neutron-scattering data base which is interpreted in the context of spherical-optical and coupled-channels (rotational and vibrational) models. These models reasonably describe the observables but indicate rather large energy-dependent parameter trends at low energies similar to those previously reported near the peak of the So strength function in studies at this laboratory. The physical implications of the measurements and models are discussed including deformation, coupling, dispersive and asymmetry effects

  14. Super austenitic stainless steels - a promising replacement for the currently used type 316L stainless steel as the construction material for flue-gas desulphurization plant

    Energy Technology Data Exchange (ETDEWEB)

    Rajendran, N.; Rajeswari, S. [University of Madras, Madras (India). Dept. of Analytical Chemistry

    1996-12-15

    Potentiodynamic anodic cyclic polarization experiments on type 316L stainless steel and 6Mo super austenitic stainless steels were carried out in simulated flue-gas desulphurization (FGD) environment in order to assess the localized corrosion resistance. The pitting corrosion resistance was higher in the case of the super austenitic stainless steel containing 6Mo and a higher amount of nitrogen. The accelerated leaching study conducted for the alloys showed that the super austenitic stainless steels have a little tendency for leaching of metal ions such as iron, chromium and nickel at different impressed potentials. This may be due to surface segregation of nitrogen as CrN, which would, in turn, enrich a chromium and molybdenum mixed oxide film and thus impede the release of metal ions. The present study indicates that the 6Mo super austenitics can be adopted as a promising replacement for the currently used type 316L stainless steel as the construction material for FGD plants.

  15. Chemical Stability of Chromium Carbide and Chromium Nitride Powders Compared with Chromium Metal in Synthetic Biological Solutions

    OpenAIRE

    Tao Jiang; Inger Odnevall Wallinder; Gunilla Herting

    2012-01-01

    Chromium carbide (Cr-C) and chromium nitride (Cr-N) powders were compared with a chromium metal powder (Cr-metal) to evaluate their chemical stability in solution. All three powders were exposed in five different synthetic biological solutions of varying pH and chemical composition simulating selected human exposure conditions. Characterisation of the powders, using GI-XRD, revealed that the predominant bulk crystalline phases were Cr7C3 and Cr2N for Cr-C and Cr-N respectively. The outermost ...

  16. Microstructure and Hardness of High Temperature Gas Nitrided AISI 420 Martensitic Stainless Steel

    Directory of Open Access Journals (Sweden)

    Ibrahim Nor Nurulhuda Md.

    2014-07-01

    Full Text Available This study examined the microstructure and hardness of as-received and nitrided AISI 420 martensitic stainless steels. High temperature gas nitriding was employed to treat the steels at 1200°C for one hour and four hours using nitrogen gas, followed by furnace cooled. Chromium nitride and iron nitride were formed and concentrated at the outmost surface area of the steels since this region contained the highest concentration of nitrogen. The grain size enlarged at the interior region of the nitrided steels due to nitriding at temperature above the recrystallization temperature of the steel and followed by slow cooling. The nitrided steels produced higher surface hardness compared to as-received steel due to the presence of nitrogen and the precipitation of nitrides. Harder steel was produced when nitriding at four hours compared to one hour since more nitrogen permeated into the steel.

  17. Microstructural Characterization and the Effect of Phase Transformations on Toughness of the UNS S31803 Duplex Stainless Steel Aged Treated at 850 °C

    OpenAIRE

    Igor Zucato; Margarete C. Moreira; Izabel F. Machado; Susana M. Giampietri Lebrão

    2002-01-01

    Duplex stainless steels, with ferritic-austenitic microstructure, have excellent mechanical properties and corrosion resistance. However, when duplex stainless steels are exposed to temperatures between 600 and 1000 °C, some phase transformations can occur such as chromium nitrides precipitation, chromium carbides precipitation and the sigma phase formation. The formation of such compounds leads to loss in both corrosion resistance and fracture toughness. The negative effects of the formation...

  18. Stainless Steel Bipolar Plates Deposited with Multilayer Films for PEMFC Applications

    Science.gov (United States)

    Cho, Hyun; Yun, Young-Hoon

    2013-08-01

    A chromium nitride (CrN, Cr2N)/chromium (Cr)/indium-tin-oxide (ITO) system and a gold (Au)/titanium (Ti) system were separately deposited using a sputtering method and an E-beam method, respectively, onto stainless steel 316 and 304 plates. The XRD patterns of the deposited stainless steel plates showed the crystalline phase of typical indium-tin oxide and of metallic phases, such as chromium, gold, and the metal substrate, as well as those of external chromium nitride films. The nitride films were composed of two metal nitride phases that consisted of CrN and Cr2N compounds. The surface morphologies of the modified stainless steel bipolar plates were observed using atomic force microscopy and FE-SEM. The chromium nitride (CrN, Cr2N)/chromium (Cr)/indium-tin-oxide (ITO) multilayer that was formed on the stainless steel plates had a surface microstructural morphology that consisted of fine columnar grains 10 nm in diameter and 60 nm in length. The external gold films that were formed on the stainless steel plates had a grain microstructure approximately 100 nm in diameter. The grain size of the external surface of the stainless steel plates with the gold (Au)/titanium (Ti) system increased with increasing gold film thickness. The electrical resistances and water contact angles of the stainless steel bipolar plates that were covered with the multilayer films were examined as a function of the thickness of the ITO film or of the external gold film. In the corrosion test, ICP-MS results indicated that the gold (Au)/titanium (Ti) films showed relatively excellent chemical stability after exposure to H2SO4 solution with pH 3 at 80 °C.

  19. High chromium martensitic stainless linepipes

    Energy Technology Data Exchange (ETDEWEB)

    Asahi, H.; Muraki, T.; Inoue, H.; Tamehiro, H. [Nippon Steel Corp., Futtsu, Chiba (Japan). Steel Research Labs.

    1996-12-01

    Effects of chemical compositions on major properties of high Cr martensitic stainless steels with low C content for linepipe were investigated. Cr to CO{sub 2}-corrosion, Ni and N to low temperature toughness in HAZ and Mo to SSC resistances were clarified to be major governing factors. Three steels with different targeted performs which were developed based on the fundamental study results were easily arc-welded without pre-heating and showed good performance for both the base metal and heat affected zone of the weld. Galvanic corrosion in welded portion and hydrogen embrittlement under cathodic protection condition were also found not to be a serious problem.

  20. Reproductive toxicological aspects of chromium in males

    International Nuclear Information System (INIS)

    To expand our present understanding of the effects of chromium on male fertility a number of studies were designed to achieve this through the use of chromium intoxicated experimental animals and through investigation of sexual hormones and sperm quality in welders. Also in view of the lack of an experimental model for effects of noxious substance on the epididymal spermatozoa the main objectives of the series of studies reviewed here were: A. To establish a model for evaluation of epididymal sperm count and motility in the rat. B. To investigate and compare the effects of tri- and hexavalent chromium on epididymal spermatozoa. Further to describe the effects of low-dose long-time exposure of rats to the most toxicological interesting chromium oxidative state - hexavalent chromium. C. By the use of autoradiography and γ-countinuing to expand the present knowledge on the distribution of chromium in the body with special reference to the male reproductive organs. D. To describe the effects of exposure to hexavalent chromium in welding fume on levels of sexual hormones and semen parameters in welders. (EG)

  1. Synthesis of Chromium (Ⅲ) 5-aminosalicylate

    Institute of Scientific and Technical Information of China (English)

    LI Wei; HAO Er-jun; JIANG Yu-qin

    2004-01-01

    As we all known that diabetes is a chronic disease with major health consequences.Research has revealed that the occurrence of diabetes have great thing to do with the chromium deficient. Almost 40 years after the first report of glucose tolerance factor(GTF) [1], no conclusive evidence for an isolable ,biologically active form of chromium exited. Three materials have been proposed to be the biologically active form of chromium: "glucose tolerance factor", chromium Picolinate and low-molecular-weight chromium-binding substance (LWMCr) [2] . So there is potential for the design of new chromium drugs .5-Aminosalicylic acid (5-ASA) is identified as an active component in the therapy of inflammatory bowel disease (IBD) such as Crohn's disease and ulcerative colitis . The therapeutic action of 5-ASA is believed to be coupled to its ability to act as a free radical scavenger [3-4],acting locally on the inflamed colonic mucosa [5-7]. However, the clinical use of 5-ASA is limited, since orally administered 5-ASA is rapidly and completely absorbed from the upper gastrointestinal tract and therefore the local therapeutic effects of 5-ASA in the colon is hardly expected.In this paper, we report the synthesis of chromium(Ⅲ)5-aminosalicylate from 5-ASA and CrCl3. 6H2O.The synthesis route is as follow:The complex has been characterized by elemental analysis, IR spectra, X-ray powder diffractionand TG-DTA . They indicate that the structure is tris(5-ASA) Chromium . Experiments show that thecomplex has a good activity for supplement tiny dietary chromium, lowering blood glucose levels,lowering serum lipid levels and in creasing lean body mass .

  2. Biodegradation of nickel and chromium from space maintainers: An in vitro study

    Directory of Open Access Journals (Sweden)

    Bhaskar V

    2010-03-01

    Full Text Available Band materials are often used in the practice of pediatric dentistry. Nickel and Chromium are the main ingredients of these materials. The potential health hazards of nickel and chromium and their compounds have been the focus of attention for more than 100 years. It has established that these metals could cause hypersensitivity. The study was undertaken to analyze in vitro biodegradation of space maintainers made out of stainless steel band materials from manufacturers Dentaurum and Unitek. The leaching effect simulating the use of one, two, three, and four space maintainers in clinical practice was studied by keeping the respective number of space maintainers in the artificial saliva incubating at 37°C and analyzing for nickel and chromium release after 1,7,14,21 and 28 days using atomic absorption spectrophotometer. Results showed that there was measurable release of both nickel and chromium which reached maximum level at the end of 7 days which was statistically significant (P < 0.05 and was very much below the dietary average intake even for four bands used and was not capable of causing any toxicity.

  3. Experimental evaluation of chromium-carbide-based solid lubricant coatings for use to 760 C

    Science.gov (United States)

    Dellacorte, Christopher

    1987-01-01

    A research program is described which further developed and investigated chromium carbide based self-lubricating coatings for use to 760 C. A bonded chromium carbide was used as the base stock because of the known excellent wear resistance and the chemical stability of chromium carbide. Additives were silver and barium fluoride/calcium fluoride eutectic. The three coating components were blended in powder form, applied to stainless steel substrates by plasma spraying and then diamond ground to the desired coating thickness. A variety of coating compositions was tested to determine the coating composition which gave optimum tribological results. Coatings were tested in air, helium, and hydrogen at temperatures from 25 to 760 C. Several counterface materials were evaluated with the objective of discovering a satisfactory metal/coating sliding combination for potential applications, such as piston ring/cylinder liner couples for Stirling engines. In general, silver and fluoride additions to chromium carbide reduced the friction coefficient and increased the wear resistance relative to the unmodified coating. The lubricant additives acted synergistically in reducing friction and wear.

  4. LASER SURFACE ALLOYING OF A MILD STEEL FOR CORROSION RESISTANCE IMPROVEMENT

    OpenAIRE

    Fouquet, F.; Renaud, L.; Millet, J.; Mazille, H.

    1991-01-01

    Surface alloys were produced by laser melting of different predeposits into the outer part of a mild steel substrate. Three types of coatings were used : electroless nickel (containing phosphorous), electroless nickel in which chromium carbide particles were introduced during deposition and duplex coatings made of, first, a nickel layer (electroless or electrodeposited) and then, a chromium layer. The surface alloying treatments were performed using a cw high power CO2 laser and the multiple ...

  5. Chromium in leather footwear-risk assessment of chromium allergy and dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob P; Strandesen, Maria; Poulsen, Pia B;

    2012-01-01

    Background. Chromium-tanned leather footwear, which releases >3 ppm hexavalent Cr(VI), may pose a risk of sensitizing and eliciting allergic dermatitis. Objectives. To determine the content and potential release of chromium in leather footwear and to discuss the prevention of chromium contact...... allergy and dermatitis. Methods. Sixty pairs of leather shoes, sandals and boots (20 children's, 20 men's, and 20 women's) were purchased in Copenhagen and examined with X-ray fluorescence spectroscopy. Chromium was extracted according to the International Standard, ISO 17075. The detection level for Cr......(VI) was 3 ppm. Results. Chromium was identified in 95% of leather footwear products, the median content being 1.7% (range 0-3.3%). No association with store category or footwear category was found. A tendency for there to be a higher chromium content in footwear with high prices was shown (p(trend) = 0...

  6. Characteristics of chromium-allergic dermatitis patients prior to regulatory intervention for chromium in leather

    DEFF Research Database (Denmark)

    Bregnbak, David; Thyssen, Jacob P; Zachariae, Claus;

    2014-01-01

    BACKGROUND: Chromium-tanned leather articles currently constitute the most important cause of contact allergy to chromium in Denmark. A regulation on the content of hexavalent chromium in leather was adopted in November 2013 by the EU member states. OBJECTIVES: To characterize patients with...... chromium allergy and their disease, to serve as a baseline for future studies on the potential effect of the new regulation on chromium in leather. METHODS: A questionnaire case-control study was performed on 155 dermatitis patients with positive patch test reactions to potassium dichromate and a matched...... control group of 621 dermatitis patients. Comparisons were made by use of a χ(2) -test and the Mann-Whitney U-test. Logistic regression analyses were used to test for associations. RESULTS: Sixty-six per cent of chromium-allergic patients had a positive history of contact dermatitis caused by leather...

  7. Oxidation of a novel CeO{sub 2}-dispersed chromium coating in wet air

    Energy Technology Data Exchange (ETDEWEB)

    Peng, X.; Yan, J.; Zheng, L.; Wang, F. [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China)

    2011-06-15

    An electrodeposited Ni-CeO{sub 2} composite was used as a ''precursor film'' for a novel CeO{sub 2}-dispersed chromium coating deposited using a traditional pack cementation method. The substrate was a carbon steel. For comparison, chromium coatings were also prepared on the untreated and pure Ni-film-treated carbon steel using the same pack cementation conditions. Oxidation in 5% O{sub 2} + 40% H{sub 2}O + N{sub 2} at 900 C showed that, compared to the CeO{sub 2}-free coating counterparts, the CeO{sub 2}-dispersed chromium coating exhibited greatly increased oxidation resistance, owing to the development of a denser and more slowly growing chromia scale. The slow growth of the scale was correlated with the CeO{sub 2} dispersion exerting the so-called ''reactive elemental effect (REE)'' on oxidation. The oxidation mechanisms in wet air of the various types of coatings were compared to those in dry air and are fully discussed in this work. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Determination of chromium and molybdenum with 2-(5-bromopyridylazo)-5-diethylaminophenol by reversed-phase liquid chromatography

    International Nuclear Information System (INIS)

    The reversed-phase liquid chromatographic determination of chromium(III) and molybdenum(VI) chelates with 2-(5-bromopyridylazo)-5-diethylaminophenol was investigated. The metal chelates in 50% ethanol solution were separated within 12 min by using methanol -tetrahydrofuran - water (10 + 15 + 75) containing 0.01 M lithium sulphate and 5 x 10-3M Tris buffer (pH 7.7) as the mobile phase at a flow-rate of 1.0 ml min-1, and were detected at 600 nm. The detection limits for chromium and molybdenum are 0.066 and 0.12 ng, respectively. The method has been applied to the determination of chromium and molybdenum in alloy steel and waste water samples. (author)

  9. Chromium intensification of a processed dental radiograph

    International Nuclear Information System (INIS)

    This study was undertaken to determine (1) the usefulness of chromium intensifier to improve the diagnostic quality of light radiograph; (2) the effect of chromium intensifier on density contrast; and (3) the effect of various chemical concentrations on density. The following results obtained: 1. CHROMIUM INTENSIFIER is useful for intensifying and improving the diagnostic quality of a light dental radiograph. 2. The degree of intensification can be controlled by varying bleaching time, repeating the processing, varying the proportions of the potassium bicarbonate and hydrochloric acid solutions. 3. The image produced is black and permanent. 4. The intensifier increases density and contrast

  10. 75 FR 49467 - Stainless Steel Sheet and Strip in Coils From Taiwan: Preliminary Results and Rescission in Part...

    Science.gov (United States)

    2010-08-13

    ... percent nickel, 18 percent chromium, and 46 percent iron, and is most notable for its resistance to high...\\ Arnokrome III is a trademark of the Arnold Engineering Company. Certain electrical resistance alloy steel is... excluded from the scope of the order. This high-strength, ductile stainless steel product is...

  11. EXAFS investigation of low temperature nitrided stainless steel

    DEFF Research Database (Denmark)

    Oddershede, Jette; Christiansen, Thomas; Ståhl, Kenny;

    2008-01-01

    Low temperature nitrided stainless steel AISI 316 flakes were investigated with EXAFS and X-ray diffraction analysis. The stainless steel flakes were transformed into a mixture of nitrogen expanded austenite and nitride phases. Two treatments were carried out yielding different overall nitrogen...... contents: (1) nitriding in pure NH3 and (2)nitriding in pure NH3 followed by reduction in H2. The majority of the Cr atoms in the stainless steel after treatment 1 and 2 was associated with a nitrogen–chromium bond distance comparable to that of the chemical compound CrN. The possibility of the occurrence...

  12. Chromium (VI) adsorption on boehmite

    Energy Technology Data Exchange (ETDEWEB)

    Granados-Correa, F. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)], E-mail: fgc@nuclear.inin.mx; Jimenez-Becerril, J. [Instituto Nacional de Investigaciones Nucleares, Apartado Postal 18-1027 Col., Escandon, Delegacion Miguel Hidalgo, C.P. 11801 Mexico, D.F. (Mexico)

    2009-03-15

    Boehmite was synthesized and characterized in order to study the adsorption behavior and the removal of Cr(VI) ions from aqueous solutions as a function of contact time, initial pH solution, amount of adsorbent and initial metal ion concentration, using batch technique. Adsorption data of Cr(VI) on the boehmite were analyzed according to Freundlich, Langmuir and Dubinin-Radushkevich (D-R) adsorption models. Thermodynamic parameters for the adsorption system were determinated at 293, 303, 313 and 323 K temperatures. The kinetic values and thermodynamic parameters from the adsorption process show that the Cr(VI) ions adsorption on boehmite is an endothermic and spontaneous process. These results show that the boehmite could be considered as a potential adsorbent for chromium ions in aqueous solutions.

  13. Chromium – An essential mineral

    Directory of Open Access Journals (Sweden)

    Merlin D Lindemann

    2009-09-01

    Full Text Available The status of chromium (Cr is not a new question. Cr is clearly an essential nutrient; this is a position that has been held for over three decades by individual scientists, groups of scientists, and governmental committees. The most uniform response across species with regard to Cr deficiency symptoms that are responsive to Cr supplementation are alterations in glucose metabolism with special reference to peripheral tissue sensitivity to insulin. Because the body’s ability to control blood glucose is critical to many life functions, and loss of ability to adequately control blood glucose can lead to many health debilitations, a consequence of Cr supplementation can be improved health and reproductive outcomes as well as improved survival rate or life span.

  14. Occupational asthma due to chromium.

    Science.gov (United States)

    Leroyer, C; Dewitte, J D; Bassanets, A; Boutoux, M; Daniel, C; Clavier, J

    1998-01-01

    We describe a 28-year-old subject employed as a roofer in a construction company since the age of 19, who developed work-related symptoms of a cough, shortness of breath, wheezing, rhinitis and headaches. A description of a usual day at work suggested that the symptoms worsened while he was sawing corrugated fiber cement. Baseline spirometry was normal, and there was a mild bronchial hyperresponsiveness to carbachol. A skin patch test to chromium was negative. A specific inhalation challenge showed a boderline fall in forced expiratory volume in 1 s (FEV1) after exposure to fiber cement dust. Exposure to nebulization of potassium dichromate (K2Cr2O7), at 0.1 mg.ml-1 for 30 min, was followed by an immediate fall by 20% FEV1. Simultaneously, a significant increase in bronchial hyperresponsiveness was demonstrated. PMID:9782225

  15. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past....... Processes that potentially fractionate Cr isotopes, perhaps during deposition, burial and alteration need to be constrained.Previous studies have shown that Cr isotopes are fractionated during oxidative weathering on land, where heavy Cr isotopes are preferentially removed with Cr(VI) while residual soils...... retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...

  16. Mass transfer of corrosion products and corrosion of steel in sodium at high hydrogen concentrations

    Science.gov (United States)

    Alekseev, V. V.; Kozlov, F. A.; Sorokin, A. P.; Varseev, E. V.; Orlova, E. A.; Torbenkova, I. Yu.

    2015-10-01

    Serviceability of steels in a loop having an increased content of hydrogen is estimated. The equilibrium pressure of hydrogen in a sodium loop saturated with hydrogen is around 10 MPa at a temperature of approximately 630°C and around 100 MPa at 800°C. At the hydrogen pressure equal to 10 MPa, steel with a chromium content of 5% is serviceable to a temperature of 840°C, and steel with a chromium content of 25% is serviceable in the entire considered range of temperatures (above 600°C). At a hydrogen pressure of 80 MPa, steel containing 5% of chromium is not serviceable in the entire considered range of temperatures, and steel containing 25% of chromium is serviceable to a temperature of 830°C. The article presents the results from experimental investigations of the effect of hydrogen on corrosion and mass transfer of corrosion products in a sodium loop at the hydrogen concentration in sodium equal to 6 ppm, which were carried out in the high-temperature section of the sodium test facility (the test facility and the investigation methodology were described in the previous publications of the authors). The distributions of chromium and nickel flows toward the walls over the channel length are obtained at increased hydrogen content (around 6 ppm) and at low oxygen content (less than 2 ppm) in sodium and at a temperature of up to 780°C. For the conditions with relatively low content of oxygen and hydrogen in sodium, the experimental values of chromium flow toward the channel wall are consistent with the calculated data. This fact confirms the possibility of using the previously obtained physicochemical constants for calculating the mass transfer of chromium in high-temperature sodium loops at an increased content of hydrogen in sodium.

  17. XPS Analysis of AISI 304L Stainless Steel Surface after Electropolishing

    Directory of Open Access Journals (Sweden)

    Rokosz K.

    2015-03-01

    Full Text Available In the paper, the passive surface layers of AISI 304L after standard (EP50 and very-high-current density electropolishing (EP1000 in a mixture of orthophosphoric and sulfuric acids in a 1:4 ratio, are presented. The main finding of the presented studies is enrichment of the steel surface film in chromium: total chromium to total iron ratio was equal to 6.6 after EP50 and to 2.8 after EP1000; on the other hand, chromium compounds to iron compounds ratio was equal to 10.1 after EP50, and 3.9 after EP1000.

  18. Simultaneous determination of chromium(III) and chromium(VI) in aqueous solutions by ion chromatography and chemiluminescence detection

    DEFF Research Database (Denmark)

    Gammelgaard, Bente; Jøns, O; Nielsen, B

    1992-01-01

    A method for the simultaneous determination of chromium(iii) and chromium(vi) in a flow system based on chemiluminescence was developed. A Dionex cation-exchange guard column was used to separate chromium(iii) from chromium(vi), and chromium(vi) was reduced by potassium sulfite, whereupon both sp....... The detection limit was 0.5 micrograms l-1 for both species. Data were in agreement with Zeeman-effect background corrected atomic absorption spectrometry measurements....

  19. AEROSOL BEHAVIOR IN CHROMIUM WASTE INCINERATION

    Institute of Scientific and Technical Information of China (English)

    Suyuan Yu

    2003-01-01

    Cr2O3 is considered as the dominant incineration product during the combustion disposal of chromium waste. A hydrogen/air diffusion flame was employed to simulate the industrial process of incineration. Cr2O3 aerosols were generated inside the flame by the gas phase reaction of chromium and oxygen. Chromium came from the rapid decomposition of chromium hexacarbonyl (Cr(CO)6) at room temperature and was carried into the combustion chamber by hydrogen. Aerosol and clusters can then be easily formed in the flame by nucleation and coagulation. A two dimensional Discrete-Sectional Model (DSM) was adopted to calculate the Cr2O3 aerosol behavior. The experimental measurement method was Dynamic Light Scattering. The numerically predicted results agreed well with those of the experimental measurement. Both results show that the Cr2O3 aerosol size reached about 70 nanometers at the flame top.

  20. Potentiometry: A Chromium (III) -- EDTA Complex

    Science.gov (United States)

    Hoppe, J. I.; Howell, P. J.

    1975-01-01

    Describes an experiment that involves the preparation of a chromium (III)-EDTA compound, a study of its infrared spectrum, and the potentiometric determination of two successive acid dissociation constants. (Author/GS)

  1. Ferritic steels for French LMFBR steam generators

    International Nuclear Information System (INIS)

    Austenitic stainless steels have been widely used in many components of the French LMFBR. Up to now, ferritic steels have not been considered for these components, mainly due to their relatively low creep properties. Some ferritic steels are usable when the maximum temperatures in service do not exceed about 5300C. It is the case of the steam generators of the Phenix plant, where the exchange tubes of the evaporator are made of 2,25% Cr-1% Mo steel, stabilized or not by addition of niobium. These ferritic alloys have worked successfully since the first steam production in October 1973. For the SuperPhenix power plant, an ''all austenitic stainless alloy'' apparatus has been chosen. However, for the future, ferritic alloys offer potential for use as alternative materials in the evaporators: low alloys steels type 2,25% Cr-1% Mo (exchange tubes, tube-sheets, shells), or at higher chromium content type 9% Cr-2% Mo NbV (exchange tubes) or 12M Cr-1% Mo-V (tube-sheets). Most of these steels have already an industrial background, and are widely used in similar applications. The various potential applications of these steels are reviewed with regards to the French LMFBR steam generators, indicating that some points need an effort of clarification, for instance the properties of the heterogeneous ferritic/austenitic weldments

  2. Study on fragmentation and dissolution behavior of carbide in a hot-rolled hypereutectic high chromium cast iron

    International Nuclear Information System (INIS)

    Highlights: • The method to prepare Carbon steel/High chromium iron is totally new. • High chromium iron can achieve small plastic deformation during hot rolling process. • Carbides in high chromium irons are crushed, refined obviously and becoming isolated, which is benefit to improve the impact toughness. • The carbide fragmentation and dissolution behavior of the hot-rolled HCCI were analyzed. - Abstract: A sandwich-structured composite containing a hypereutectic high chromium cast iron (HCCI) and low carbon steel (LCS) claddings was newly fabricated by centrifugal casting, then the blank was hot-rolled into composite plate. The carbide fragmentation and dissolution behavior of the hot-rolled HCCI were analyzed. During hot rolling, significant refinement of carbides was discovered in hot-rolled HCCI specimens. The carbides were broken and partly dissolved into the austenite matrix. The results show that carbides are firstly dissolved under the action of stress. There are grooves appeared at the boundaries of the carbides. The grooves reduce the cross section of the carbide. When the cross section of the carbide reaches to the required minimum critical cross section, the carbide breaks through the tensile force. After break, carbides continue to dissolve since more interfaces between the matrix and carbides are generated. The secondary carbides precipitated due to the dissolution are index as fcc and stacking faults parallel to the {1 1 1} are observed

  3. Study on fragmentation and dissolution behavior of carbide in a hot-rolled hypereutectic high chromium cast iron

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fei; Jiang, Yehua, E-mail: jiangyehua@kmust.edu.cn; Xiao, Han; Tan, Jun

    2015-01-05

    Highlights: • The method to prepare Carbon steel/High chromium iron is totally new. • High chromium iron can achieve small plastic deformation during hot rolling process. • Carbides in high chromium irons are crushed, refined obviously and becoming isolated, which is benefit to improve the impact toughness. • The carbide fragmentation and dissolution behavior of the hot-rolled HCCI were analyzed. - Abstract: A sandwich-structured composite containing a hypereutectic high chromium cast iron (HCCI) and low carbon steel (LCS) claddings was newly fabricated by centrifugal casting, then the blank was hot-rolled into composite plate. The carbide fragmentation and dissolution behavior of the hot-rolled HCCI were analyzed. During hot rolling, significant refinement of carbides was discovered in hot-rolled HCCI specimens. The carbides were broken and partly dissolved into the austenite matrix. The results show that carbides are firstly dissolved under the action of stress. There are grooves appeared at the boundaries of the carbides. The grooves reduce the cross section of the carbide. When the cross section of the carbide reaches to the required minimum critical cross section, the carbide breaks through the tensile force. After break, carbides continue to dissolve since more interfaces between the matrix and carbides are generated. The secondary carbides precipitated due to the dissolution are index as fcc and stacking faults parallel to the {1 1 1} are observed.

  4. Electro- and hot-dip galvanized steel sheets having Cr-free treatment layer on the surface and Cr-free prepainted electrogalvanized steel sheets; Kuromu furi hyomen shori aen mekki gohan oyobi kuromu furi purekoto denki aen mekki gohan

    Energy Technology Data Exchange (ETDEWEB)

    Kanai, H.; Yamasaki, M.; Mori, Y.; Ueda, K.; Morishita, A.; Furukawa, H.; Nakazawa, M.; Ishizuka, K.; Wake, R.

    1998-05-31

    Various types of coated steel sheets, which are among the major products of Nippon Steel's sheet and coil products, have a chromate layer on those surfaces to ensure good white rust resistance and finish-coat adhesion. However, six valent chromium contained in the chromate layer is one of the environmentally un-friendly materials. In reply to our users' requirement of eliminating such materials, we have recently developed a Cr-free electrogalvanized steel sheet 'ZINKOAT-21', a Cr-free hot-dip galvanized steel sheet 'SILVERZINC-21', and a Cr-free prepainted electrogalvanized steel sheet 'VIEWKOAT-21'. The performance of those new products have been found to be enough for actual uses in comparison with the conventional coated steel sheets which contain chromium. (author)

  5. Surface nitride formation in N-implanted Cr-steels

    International Nuclear Information System (INIS)

    Nitrogen-implanted steels of different composition (mainly a variable chromium content) and structure have been studied by nuclear reaction analysis (NRA) and conversion electron Moessbauer scattering (CEMS). For every given composition and structure, the relationship between a parameter measuring the amount of iron nitride produced and the nitrogen dose retained in the near-surface region is found to be almost linear with a nearly constant positive slope. The dose threshold for iron nitride formation increases with increasing chromium content and defect concentration in the matrix. (author)

  6. Biomonitoring of genotoxic exposure among stainless steel welders

    DEFF Research Database (Denmark)

    Knudsen, Lisbeth E.; Boisen, T; Christensen, J M;

    1992-01-01

    . Environmental monitoring of welding fumes and selected metal oxides, biomonitoring of chromium and nickel in serum and urine and mutagenic activity in urine, and evaluation of semen quality were also done. Manual metal arc (MMA) welding and tungsten inert gas (TIG) welding were the dominant welding processes. A...... lymphocytes in exposed persons compared with non-exposed are suggested. MMA welding gave the highest exposure to chromium, an increased number of chromosomal aberrations and a decrease in SCE when compared with TIG welding. Consequently improvements in the occupational practice of stainless steel welding with...

  7. Graphitization in chromium cast iron

    OpenAIRE

    LECOMTE-BECKERS, Jacqueline; Terziev, L.; Breyer, J. P.

    1998-01-01

    Some trials with graphite Hi-Cr iron rolls have been done mainly in Japan, for the rolling of stainless steel. This material could lead to good compromise between oxidation, wear and thermal behaviour. By using thermal analysis and resistometry, the conditions for secondary graphite formation have been studied. The amount and volume of free graphite may be strongly increased by a suitable heat treatment, allowing a good thermal conductivity as well as high wear and mechanical properties.

  8. Bioremediation of chromium solutions and chromium containing wastewaters.

    Science.gov (United States)

    Malaviya, Piyush; Singh, Asha

    2016-08-01

    Cr(VI) represents a serious threat to human health, living resources and ecological system as it is persistent, carcinogenic and toxic, whereas, Cr(III), another stable oxidation state of Cr, is less toxic and can be readily precipitated out of solution. The conventional methods of Cr(VI) removal from wastewaters comprise of chemical reduction followed by chemical precipitation. However, these methods utilize large amounts of chemicals and generate toxic sludge. This necessitates the need for devising an eco-technological strategy that would use the untapped potential of the biological world for remediation of Cr(VI) containing wastewaters. Among several viable approaches, biotransformation of Cr(VI) to relatively non-toxic Cr(III) by chromium resistant bacteria offers an economical- and environment-friendly option for its detoxification. Various studies on use of Cr(VI) tolerant viable bacterial isolates for treatment of Cr(VI) containing solutions and wastewater have been reported. Therefore, a detailed account of mechanisms and processes involved in bioreduction of Cr(VI) from solutions and wastewaters by bacterial isolates are the focus of this review article in addition to a discussion on toxicity of Cr(VI) on bacterial strains and various factors affecting Cr(VI) bioreduction. PMID:25358056

  9. Corrosion Behavior of Austenitic and Duplex Stainless Steels in Lithium Bromide

    Directory of Open Access Journals (Sweden)

    Ayo Samuel AFOLABI

    2009-07-01

    Full Text Available The corrosion behavior of austenitic and duplex stainless steels in various concentrations of lithium, bromide solution was investigated by using the conventional weight loss measurement method. The results obtained show that corrosion of these steels occurred due to the aggressive bromide ion in the medium. Duplex stainless steel shows a greater resistance to corrosion than austenitic stainless steel in the medium. This was attributed to equal volume proportion of ferrite and austenite in the structure of duplex stainless steel coupled with higher content of chromium in its composition. Both steels produced electrochemical noise at increased concentrations of lithium bromide due to continuous film breakdown and repair caused by reduction in medium concentration by the alkaline corrosion product while surface passivity observed in duplex stainless steel is attributed to film stability on this steel.

  10. PLEPS study of ions implanted RAFM steels

    Science.gov (United States)

    Sojak, S.; Slugeň, V.; Egger, W.; Ravelli, L.; Petriska, M.; Veterníková, J.; Stacho, M.; Sabelová, V.

    2014-04-01

    Current nuclear power plants (NPP) require radiation, heat and mechanical resistance of their structural materials with the ability to stay operational during NPP planned lifetime. Radiation damage much higher, than in the current NPP, is expected in new generations of nuclear power plants, such as Generation IV and fusion reactors. Investigation of perspective structural materials for new generations of nuclear power plants is among others focused on study of reduced activation ferritic/martensitic (RAFM) steels. These steels have good characteristics as reduced activation, good resistance to volume swelling, good radiation, and heat resistance. Our experiments were focused on the study of microstructural changes of binary Fe-Cr alloys with different chromium content after irradiation, experimentally simulated by ion implantations. Fe-Cr alloys were examined, by Pulsed Low Energy Positron System (PLEPS) at FRM II reactor in Garching (Munich), after helium ion implantations at the dose of 0.1 C/cm2. The investigation was focused on the chromium effect and the radiation defects resistivity. In particular, the vacancy type defects (monovacancies, vacancy clusters) have been studied. Based on our previous results achieved by conventional lifetime technique, the decrease of the defects size with increasing content of chromium is expected also for PLEPS measurements.

  11. An Evaluation of Welding Processes to Reduce Hexavalent Chromium Exposures and Reduce Costs by Using Better Welding Techniques

    OpenAIRE

    Keane, Michael J.

    2014-01-01

    A group of stainless steel arc welding processes was compared for emission rates of fume and hexavalent chromium, and costs per meter length of weld. The objective was to identify those with minimal emissions and also compare relative labor and consumables costs. The selection included flux-cored arc welding (FCAW), shielded-metal arc welding (SMAW), and multiple gas metal arc welding (GMAW) processes. Using a conical chamber, fumes were collected, and fume generation rates and hexavalent chr...

  12. Phosphate coating on stainless steel 304 sensitized

    International Nuclear Information System (INIS)

    The stainless steel 304 can be sensitized when welding processes are applied, that causes the precipitation of chromium carbide in the grain limits, being promoted in this way the formation of galvanic cells and consequently the corrosion process. Using a phosphate coating is possible to retard the physiochemical damages that can to happen in the corrosion process. The stainless steel 304 substrate sensitized it is phosphate to base of Zn-Mn, in a immersion cell very hot. During the process was considered optimization values, for the characterization equipment of X-rays diffraction and scanning electron microscopy was used. The XRD technique confirmed the presence of the phases of manganese phosphate, zinc phosphate, as well as the phase of the stainless steel 304. When increasing the temperature from 60 to 90 C in the immersion process a homogeneous coating is obtained. (Author)

  13. New ferritic steels for advanced steam plants

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, K.H; Koenig, H. [GEC ALSTHOM Energie GmbH, Nuremberg (Germany)

    1998-12-31

    During the last 15-20 years ferritic-martensitic 9-12 % chromium steels have been developed under international research programmes which permit inlet steam temperatures up to approx. 625 deg C and pressures up to about 300 bars, thus leading to improvements in thermal efficiency of around 8 % and a CO{sub 2} reduction of about 20 % versus conventional steam parameters. These new steels are already being applied in 13 European and 34 Japanese power stations with inlet steam temperature up to 610 deg C. This presentation will give an account of the content, scope and results of the research programmes and of the experience gained during the production of components which have been manufactured from the new steels. (orig.) 13 refs.

  14. Diminishing Chromium Use on Combined Chromium-Gambier Tanning Process Upon the Characteristics of Tanned Leather

    Directory of Open Access Journals (Sweden)

    A. Kasim

    2014-04-01

    Full Text Available The research was aimed to investigate the influence of minimizing chromium use on combined chromium-gambier process upon the characteristics of tanned leather. At the first stage of tanning process, chromium was used and in the second stage it was replaced by gambier. The raw material used was dried saline-preserved goat skin. The treatments applied on the tanning process were the different concentrations of chromium ranging from the highest level of 6% to the lowest level of 1% which was then re-tanned by using 8% concentration of gambier. The examination parameters included chemical and physical properties as well as visual investigation on the tanned leather in accordance with SNI-06-0463-1989-A. The result showed that the tanning process by using 2% chromium in the first step and 8% gambier in the second step was a treatment combination producing tanned leather that met the standard. The examination on tanned leather resulted from such treatment showed 56.33% rawhide, 17.45% of bound tannin, 31.22% of tanning level, tensile strength 386.30 kg/cm2, flexibility 31.91%, leather width 1.3 mm, density 0.75 g/cm3, the leather was quite elastic with light brownish color. In conclusion, minimizing the use of chromium in the combined tanning process of chromium and gambier can be implemented to the lowest of 2% chromium concentration and 8% gambier in the first and second step, respectively.

  15. Influence of Surface Treatment on the Corrosion Resistance of Stainless Steel in Simulated Human Body Environment

    Institute of Scientific and Technical Information of China (English)

    Esmaeil Jafari; Mohammad Jafar Hadianfard

    2009-01-01

    In the present research, the influence of chromium enrichment by surface treatment on corrosion resistance of type 316L stainless steel in body environment was investigated. For this study, weight loss test during 18 months, cyclic and liner polarization tests before and after surface treatment and metallography by electron and light microscopy were used to evaluate the effectiveness of the proposed method. In addition, X-ray photoelectron spectroscopy (XPS) method was used to determine the chromium concentration in the surface layer after surface treatment. Results show that the surface treatment has improved corrosion resistance of the type 316L stainless steel in body environment.

  16. Hexavalent chromium [Cr(VI)] removal by the electrochemical ion-exchange process.

    Science.gov (United States)

    Dharnaik, Amit Shivputra; Ghosh, Pranab Kumar

    2014-01-01

    In the present investigation, the performance of a laboratory-scale plate and frame-type electrochemical ion-exchange (EIX) cell on removal ofhexavalent chromium from synthetic wastewater containing 5 mg/l of Cr(VI) was evaluated under varying applied voltages. Ruthenium dioxide-coated titanium plate (RuO2/Ti) was used as anode and stainless steel plates as cathode. The EIX cell was run at different hydraulic retention time (HRT). Before using in the electrochemical cell, the capacity of ion-exchange resin was evaluated through kinetic and isotherm equilibrium tests in batch mode. The batch kinetic study result showed that the equilibrium time for effective ion exchange with resin is 2 h. The isotherm equilibrium data fit well to both Freundlich and Langmuir isotherms. Maximum capacity (qm) of resin calculated from Langmuir isotherm was 71.42 mg/g. Up to 99% of chromium removal was noticed in the EIX cell containing fresh resin at applied voltages of 10 V and higher. Migration of chromium ion to anode chamber was not noticed while performing the experiment with fresh resin. As high as 50% removal of chromium was observed from the middle chamber containing exhausted resin at an applied voltage of 25 V when the influent flow rate was maintained at 45 min of HRT. The performance of the reactor was increased to 72% when the influent flow rate was decreased to maintain at 90 min of HRT. Build-up of chromium in the anode chamber took place when exhausted resin was used in the process. PMID:25145180

  17. Investigation of alternative phosphating treatments for nickel and hexavalent chromium elimination

    International Nuclear Information System (INIS)

    The phosphating processes are widely used in industry as surface treatments for metals, especially for low thickness plates, improving the adhesion between the metallic surface and the paint coating, and increasing the durability of paint systems against corrosion attacks. The tricationic phosphates containing zinc, nickel and manganese are commonly applied on steel. There is much discussion about the replacement of nickel by another element in order to have an environmentally friendly phosphating process. Niobium as a replacement for nickel has been evaluated. The most significant environmental impacts of phosphating processes are related to the presence of nickel and hexavalent chromium used in the process, this last as a passivation treatment. Nickel and hexavalent chromium are harmful to human and environment leading to contamination of water and soil. In the present study phosphate layers containing zinc, manganese and niobium have been evaluated and characterized on galvanized steel, and the results were compared with phosphates containing zinc, manganese and nickel, or a bicationic phosphate layer with zinc and manganese. Although the use of hexavalent chromium is not recommended worldwide, it is still used in processes for sealing the porosity of phosphate layers. This element is carcinogenic and has been associated with various diseases. Due to the passivation characteristics of niobium, this study also evaluated the tricationic bath containing niobium ammonium oxalate as a passivation treatment. The results showed that it could act as a replacement for the hexavalent chromium. The results of the present study showed that formulations containing niobium are potential replacements for hexavalent chromium and similar corrosion protection was obtained for the phosphate containing nickel or that with niobium. The morphology observed by scanning electron microscopy, gravimetric tests, porosity and adhesion evaluation results indicated that the phosphate

  18. Lateral stress evolution in chromium sulfide cermets with varying excess chromium

    Science.gov (United States)

    Petel, O. E.; Appleby-Thomas, G. J.; Wood, D. C.; Capozzi, A.; Nabavi, A.; Goroshin, S.; Frost, D. L.; Hazell, P. J.

    2016-04-01

    The shock response of chromium sulfide-chromium, a cermet of potential interest as a matrix material for ballistic applications, has been investigated at two molar ratios. Using a combustion synthesis technique allowed for control of the molar ratio of the material, which was investigated under near-stoichiometric (cermet) and excess chromium (interpenetrating composite) conditions, representing chromium:sulfur molar ratios of 1.15:1 and 4:1, respectively. The compacts were investigated via the plate-impact technique, which allowed the material to be loaded under a one-dimensional state of strain. Embedded manganin stress gauges were employed to monitor the temporal evolution of longitudinal and lateral components of stress in both materials. Comparison of these two components has allowed assessment of the variation of material shear strength both with impact pressure/strain-rate and time for the two molar ratio conditions. The two materials exhibited identical material strength despite variations in their excess chromium contents.

  19. Steel Planning

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    China releases a new plan for the iron and steel industry centered on industrial upgrades The new 12th Five-Year Plan (2011-15) for China’s iron and steel industry, recently released on the website of the Ministry of Industry and Information

  20. Dissolutions of oxide dispersion strengthened ferritic steels in various nitric acid solutions. Martensitic 9Cr-ODS steels

    International Nuclear Information System (INIS)

    Corrosion resistance of fuel pin cladding tube materials is one of the most important properties to design advanced aqueous reprocessing process. The martensitic oxide dispersion strengthened ferritic steel, named as '9Cr-ODS' steel, is the primary candidate material for high burnup fuel pin cladding tube in fast reactor cycle system. Because 9Cr-ODS steel contains lower chromium than stainless steels, oxidizing species such as high nitric acid concentrations and metallic ions need to reduce its corrosion rate. In nitric acid medium in contact with 9Cr-ODS steel, both nitric acid and metallic ions concentrations gradually change and stabilize protective passive layer effectively in rotary drum type continuous dissolvers. (author)

  1. Iron -chromium alloys and free surfaces: from ab initio calculations to thermodynamic modeling

    International Nuclear Information System (INIS)

    Ferritic steels possibly strengthened by oxide dispersion are candidates as structural materials for generation IV and fusion nuclear reactors. Their use is limited by incomplete knowledge of the iron-chromium phase diagram at low temperatures and of the phenomena inducing preferential segregation of one element at grain boundaries or at surfaces. In this context, this work contributes to the multi-scale study of the model iron-chromium alloy and their free surfaces by numerical simulations. This study begins with ab initio calculations of properties related to the mixture of atoms of iron and chromium. We highlight complex dependency of the magnetic moments of the chromium atoms on their local chemical environment. Surface properties are also proving sensitive to magnetism. This is the case of impurity segregation of chromium in iron and of their interactions near the surface. In a second step, we construct a simple energy model for high numerical efficiency. It is based on pair interactions on a rigid lattice to which are given local chemical environment and temperature dependencies. With this model, we reproduce the ab initio results at zero temperature and experimental results at high temperature. We also deduce the solubility limits at all intermediate temperatures with mean field approximations that we compare to Monte Carlo simulations. The last step of our work is to introduce free surfaces in our model. We then study the effect of ab initio calculated bulk and surface properties on surface segregation.Finally, we calculate segregation isotherms. We therefore propose an evolution model of surface composition of iron-chromium alloys as a function of bulk composition. which are given local chemical environment and temperature dependencies. With this model, we reproduce the ab initio results at zero temperature and experimental results at high temperature. We also deduce the solubility limits at all intermediate temperatures with mean field approximations that

  2. Chromium carbide coatings obtained by the hybrid PVD methods

    Directory of Open Access Journals (Sweden)

    M. Richert

    2010-11-01

    Full Text Available Purpose: With the use of the Arc-PVD and Arc-EB PVD hybrid method, the chromium carbide coatings were deposited on steel substrate. Two kinds of coatings were obtained. The nanostructure coatings were formed by deposition of chromium carbide films by Arc PVD evaporation technique. The multilayer coatings were produced by Arc-EB PVD hybrid technology. In the second case the amorphous phase in majority was found in samples, identified by X-ray investigations.Design/methodology/approach: The Arc PVD and combination Arc-EB PVD methods were used for carbide coatings deposition. The special hybrid multisource device, produced in the Institute for Sustainable Technologies – National Research Institute (ITeE –PIB in Radom, was used for sample deposition. The microstructures of coatings were investigated by JEM 20101 ARP transmission electron microscopy (TEM, TESLA BS500 scanning electron microscopy (SEM and Olympus GX50 optical microscopy (MO. The X-ray diffraction was utilized to identify phase configuration in coatingsFindings: The microstructure of deposited coatings differs depending on the deposition method used. The Arc PVD deposition produced nanometric coatings with the Cr3C2, Cr23C6, Cr7C3 and CrC carbides built from nanometric in size clusters. In the case of the Arc-EB PVD hybrid technology in majority of cases the amorphous microstructure of coatings was found. The hybrid coatings consist of alternating layers of Ni/Cr-Cr3C2.Practical implications: The performed investigations provide information, which could be useful in the industrial practice for the production of wear resistant coatings on different equipments and tools.Originality/value: It was assumed that by using different kinds of PVD methods the different microstructures of coatings could be formed.

  3. Abrasion Resistance of as-Cast High-Chromium Cast Iron

    Directory of Open Access Journals (Sweden)

    Pokusová Marcela

    2014-12-01

    Full Text Available High chromium cast irons are widely used as abrasion resistant materials. Their properties and wear resistance depend on carbides and on the nature of the matrix supporting these carbides. The paper presents test results of irons which contain (in wt.% 18-22 Cr and 2-5 C, and is alloyed by 1.7 Mo + 5 Ni + 2 Mn to improve the toughness. Tests showed as-cast irons with mostly austenitic matrix achieved hardness 36-53 HRC but their relative abrasion-resistance was higher than the tool steel STN 19436 heat treated on hardness 60 HRC.

  4. Ion-nitriding of austenitic stainless steels

    International Nuclear Information System (INIS)

    Although ion-nitriding is an extensively industrialized process enabling steel surfaces to be hardened by nitrogen diffusion, with a resulting increase in wear, seizure and fatigue resistance, its direct application to stainless steels, while enhancing their mechanical properties, also causes a marked degradation in their oxidation resistance. However, by adaption of the nitriding process, it is possible to maintain the improved wear resistant properties while retaining the oxidation resistance of the stainless steel. The controlled diffusion permits the growth of a nitrogen supersaturated austenite layer on parts made of stainless steel (AISI 304L and 316L) without chromium nitride precipitation. The diffusion layer remains stable during post heat treatments up to 650 F for 5,000 hrs and maintains a hardness of 900 HV. A very low and stable friction coefficient is achieved which provides good wear resistance against stainless steels under diverse conditions. Electrochemical and chemical tests in various media confirm the preservation of the stainless steel characteristics. An example of the application of this process is the treatment of Reactor Control Rod Cluster Assemblies (RCCAs) for Pressurized Water Nuclear Reactors

  5. The enriched chromium neutrino source for GALLEX

    International Nuclear Information System (INIS)

    The preparation and study of an intense source of neutrinos in the form of neutron irradiated materials which are enriched in Cr-50 for use in the GALLEX solar neutrino experiment are discussed. Chromyl fluoride gas is enriched in the Cr-50 isotope by gas centrifugation and subsequently converted to a very stable form of chromium oxide. The results of neutron activation analyses of such chromium samples indicate low levels of any long-lived activities, but show that short-lived activities, in particular Na-24, may be of concern. These results show that irradiating chromium oxide enriched in Cr-50 is preferable to irradiating either natural chromium or argon gas as a means of producing a neutrino source to calibrate the GALLEX detector. These results of the impurity level analysis of the enriched chromyl fluoride gas and its conversion to the oxide are also of interest to work in progress by other members of the Collaboration investigating an alternative conversion of the enriched gas to chromium metal. 35 refs., 12 figs., 5 tabs

  6. Serum chromium levels in gestational diabetes mellitus

    Directory of Open Access Journals (Sweden)

    P G Sundararaman

    2012-01-01

    Full Text Available Objective: To measure serum chromium level in women with gestational diabetes mellitus (GDM from Chennai, South India. Materials and Methods: Thirty women with gestational diabetes, 60 age matched controls. Inclusion criteria: Gestational age 22-28 weeks, age group 20-35 years. Exclusion Criteria: Gestational age beyond 28 weeks, malnutrition or presence of infection. Serum chromium was measured using inductive couple plasma emission spectrometer. Results: Serum chromium levels of women with GDM, 1.59+/-0.02 ng/ml (range: 0.16-4.0 ng/ml were lower than in controls (4.58+/-0.62 ng/ml; range 0.82-5.33 ng/ml (P < 0.001. However, there were no significant differences among cases and controls when subdivided by parity. Conclusions: Women with GDM from a South Indian city had lower levels of serum chromium compared to pregnant women without GDM. Studies may be done whether chromium supplementation is useful in this group of women.

  7. Occupational exposure to chromium(VI compounds

    Directory of Open Access Journals (Sweden)

    Jolanta Skowroń

    2015-07-01

    Full Text Available This article discusses the effect of chromium(VI (Cr(VI on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV for chromium(VI of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL document chromium(VI concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2–14 cases per 1000 exposed workers. Exposure to chromium(VI compounds expressed in Cr(VI of 0.01 mg Cr(VI/m3 is responsible for the increased number of lung cancer cases in 1–6 per 1000 people employed in this condition for the whole period of professional activity. Med Pr 2015;66(3:407–427

  8. [Occupational exposure to chromium(VI) compounds].

    Science.gov (United States)

    Skowroń, Jolanta; Konieczko, Katarzyna

    2015-01-01

    This article discusses the effect of chromium(VI) (Cr(VI)) on human health under conditions of acute and chronic exposure in the workplace. Chromium(VI) compounds as carcinogens and/or mutagens pose a direct danger to people exposed to them. If carcinogens cannot be eliminated from the work and living environments, their exposure should be reduced to a minimum. In the European Union the proposed binding occupational exposure limit value (BOELV) for chromium(VI) of 0.025 mg/m³ is still associated with high cancer risk. Based on the Scientific Commitee of Occupational Exposure Limits (SCOEL) document chromium(VI) concentrations at 0.025 mg/m³ increases the risk of lung cancer in 2-14 cases per 1000 exposed workers. Exposure to chromium(VI) compounds expressed in Cr(VI) of 0.01 mg Cr(VI)/m3; is responsible for the increased number of lung cancer cases in 1-6 per 1000 people employed in this condition for the whole period of professional activity. PMID:26325053

  9. Flashlamp-pumped lasing of chromium-doped GSG garnet

    International Nuclear Information System (INIS)

    The implications for the practical use of chromium:GSGG in lamp-pumped tunable lasers are discussed in this paper. The authors report here some major improvements in the performance of the flashlamp-pumped chromium:GSGG laser

  10. Surface Chemistry and Spectroscopy of Chromium in Inorganic Oxides

    OpenAIRE

    Weckhuysen, B. M.; Wachs, I.E.; Schoonheydt, R. A.

    1996-01-01

    Focuses on the surface chemistry and spectroscopy of chromium in inorganic oxides. Characterization of the molecular structures of chromium; Mechanics of hydrogenation-dehydrogenation reactions; Mobility and reactivity on oxidic surfaces.

  11. Studies of Some Novel Chromium Pyridine Dicarboxylate Complexes

    OpenAIRE

    Chauhan Jayprakash S; Patel Rameshchandra P; Pandya Ajit V

    2014-01-01

    Chromium pyridine di-carboxylate complexes are synthesized from Chromium (III) with pyridine 2, 6- dicarboxylic acid, pyridine 2, 3 and 2, 5- dicarboxylic acids. Chromium forms colored complexes. Chromium (III) forms a violate complex with pyridine 2, 6- dicarboxylic acid and purple violate complex with pyridine 2, 3 and 2, 5- dicarboxylic acids. The job’s method indicates metal ligand ratio to be 1:2. The interpretation of UV-VIS spectra indicates octahedral geometry and IR spectra give clue...

  12. Determination of chromium combined with DNA, RNA and proteins in chromium-rich brewer's yeast by NAA

    International Nuclear Information System (INIS)

    The content of chromium in the DNA, RNA and protein fractions separated from chromium-rich and normal brewer's yeast was determined by neutron activation analysis (NAA). Our results show that the extracted relative amounts and concentrations of DNA, RNA and proteins have no significant difference for two types of yeast, but the chromium content in DNA, RNA and proteins fractions extracted from the chromium-rich yeast are substantially higher than those from the normal. In addition, the concentration of chromium in DNA is much higher than that in RNA and proteins. It is evident that the inorganic chromium compounds can enter the yeast cell during the yeast cultivation in the chromium-containing culture medium and are converted into organic chromium species, which are combined with DNA, RNA and proteins. (author)

  13. Chromium allergy and dermatitis: prevalence and main findings

    DEFF Research Database (Denmark)

    Bregnbak, David; Johansen, Jeanne D.; Jellesen, Morten Stendahl;

    2015-01-01

    The history of chromium as an allergen goes back more than a century, and includesan interventional success with national legislation that led to significant changes inthe epidemiology of chromium allergy in construction workers. The 2015 EU Leather Regulation once again put a focus on chromium...

  14. 21 CFR 73.1326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.1326 Section 73.1326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1326 Chromium hydroxide green. (a) Identity. (1) The color additive chromium hydroxide green is principally hydrated chromic sesquioxide...

  15. 21 CFR 73.2326 - Chromium hydroxide green.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium hydroxide green. 73.2326 Section 73.2326... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2326 Chromium hydroxide green. (a) Identity and specifications.The color additive chromium hydroxide green shall conform in identity and specifications to...

  16. Thermodynamic properties of chromium bearing slags and minerals. A review

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Yanping; Holappa, L.

    1996-12-31

    In this report, the thermodynamic properties of chromium bearing slags and minerals were reviewed based on the available information in the literature. It includes the analysing methods for oxidation state of chromium in slags, oxidation state of chromium and activities of chromium oxides in slags and minerals. The phase diagrams of chromium oxide systems and chromium distributions between slag and metal phases are also covered ill this review. Concerning the analysing methods, it was found that most of the available approaches are limited to iron free slag systems and the sample preparation is very sensitive to the analysing results. In silicate slags under reducing atmosphere, divalent and trivalent chromium co-exist in the slags. It is agreed that the fraction of divalent chromium to total chromium increases with higher temperature, lower slag basicity and oxygen potential. For the slags under oxidising atmosphere, trivalent, pentavalent and hexavalent states were reported to be stable. The activities of CrO and CrO{sub 1.5} were concluded to have positive deviation from ideal solution. Slag basicity has a positive effect and temperature has a negative effect on the activities of chromium oxides. The phase diagrams of the Cr-O, binary, and ternary chromium containing oxide systems have been examined systematically. The analysis shows that the data on the quaternary and quinary systems are insufficient, and require further investigation. The most important features of the chromium containing silicate slags are the large miscibility gaps and the stability of the chromite spinel. (orig.) (76 refs.)

  17. 21 CFR 73.1015 - Chromium-cobalt-aluminum oxide.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Chromium-cobalt-aluminum oxide. 73.1015 Section 73... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1015 Chromium-cobalt-aluminum oxide. (a) Identity. The color additive chromium-cobalt-aluminum oxide is a blue-green pigment obtained by calcining...

  18. Hexavalent and trivalent chromium in leather: What should be done?

    Science.gov (United States)

    Moretto, Angelo

    2015-11-01

    Trivalent chromium compounds are used for leather tanning, and chromium may be released during use of leather goods. In certain instances, small amounts of hexavalent chromium can be formed and released. Both trivalent and hexavalent chromium can elicit allergic skin reaction in chromium sensitised subjects, the latter being significantly more potent. Induction of sensitisation only occurs after exposure to hexavalent chromium. A minority of subjects are sensitised to chromium, and in a fraction of these subjects allergic skin reaction have been described after wearing leather shoes or, less frequently, other leather goods. The evidence that in all these cases the reaction is related to hexavalent chromium is not always strong. The content of hexavalent chromium in leather is regulated in European Union, but rate of release rather than content is relevant for allergic skin reaction. The role of trivalent chromium appear much less relevant if at all. Modern tanning procedure do not pose significant risk due to either hexavalent or trivalent chromium. Dismissing bad quality and worn-off leather goods is relevant in reducing or eliminating the skin reaction. It should also be pointed out that shoe components or substances other than chromium in leather may cause allergic/irritative skin reactions. PMID:26361854

  19. SAFETY OF TRIVALENT CHROMIUM COMPLEXES USED IN NUTRIENT SUPPLEMENTS

    Science.gov (United States)

    Toxicity studies regarding trivalent chromium have often been completed under conditions that are not designed to reflect conditions that would be encountered under normal physiological conditions. We have shown that the incorporation of chromium into tissues of rats from chromium chloride and chro...

  20. On the correlation between heat resistance and durable heat strength os steels

    International Nuclear Information System (INIS)

    In determining the high-temperature properties of metallic materials a combined evaluation of thermal stability and high-temperature strength is recommended, based on a comparison of limiting temperatures calculated from the parameteric thermal stability diagram and the temperature dependence of the stress-rupture strength. Criteria are proposed for harmonic alloying of materials designed for high-temperature operation in oxidizing gaseous media under static loads. Calculations based on experimental data indicate that the pearlitic steels 12X1MF, 12X2MFSR and 12X1MFB do not have satisfactory thermal stability, whereas medium- and high-chromium steels and chromium-nickel austenitic steels are characterized by a favourable thermal stability to high-temperature strength ratio. Increasing the high-temperature strength of steels improves the relationship between thermal stability and high-temperature strength. (author)

  1. Influence of manganese and nickel on properties of low-carbon steels with 13% Cr

    International Nuclear Information System (INIS)

    Studied is the influence of manganese and nickel on mechanical properties and resistance-to-corrosion of the 13% content chromium steels containing 0.1-0.2%C. It is shown that manganese introduction results is the increase of strength characteristics of hardened steels because of delta-ferrite formation suppresion and solid solution strengthening. The delayed cooling during hardening permits to increase ductility and impact strength. Low-carbon 13% content chromium steels alloyed with nickel, molybdenum and aluminium have high heat resistance at temperatures up to 500 deg C due to the precipitation of intermetallics atlading. Chrome-manganese and chrome-nickel steels have a high resistance-to-corrosion in the hardened state in the neutral and weak-acid media

  2. Strategies for chromium bioremediation of tannery effluent.

    Science.gov (United States)

    Garg, Satyendra Kumar; Tripathi, Manikant; Srinath, Thiruneelakantan

    2012-01-01

    Bioremediation offers the possibility of using living organisms (bacteria, fungi, algae,or plants), but primarily microorganisms, to degrade or remove environmental contaminants, and transform them into nontoxic or less-toxic forms. The major advantages of bioremediation over conventional physicochemical and biological treatment methods include low cost, good efficiency, minimization of chemicals, reduced quantity of secondary sludge, regeneration of cell biomass, and the possibility of recover-ing pollutant metals. Leather industries, which extensively employ chromium compounds in the tanning process, discharge spent-chromium-laden effluent into nearby water bodies. Worldwide, chromium is known to be one of the most common inorganic contaminants of groundwater at pollutant hazardous sites. Hexavalent chromium poses a health risk to all forms of life. Bioremediation of chromium extant in tannery waste involves different strategies that include biosorption, bioaccumulation,bioreduction, and immobilization of biomaterial(s). Biosorption is a nondirected physiochemical interaction that occurs between metal species and the cellular components of biological species. It is metabolism-dependent when living biomass is employed, and metabolism-independent in dead cell biomass. Dead cell biomass is much more effective than living cell biomass at biosorping heavy metals, including chromium. Bioaccumulation is a metabolically active process in living organisms that works through adsorption, intracellular accumulation, and bioprecipitation mechanisms. In bioreduction processes, microorganisms alter the oxidation/reduction state of toxic metals through direct or indirect biological and chemical process(es).Bioreduction of Cr6+ to Cr3+ not only decreases the chromium toxicity to living organisms, but also helps precipitate chromium at a neutral pH for further physical removal,thus offering promise as a bioremediation strategy. However, biosorption, bioaccumulation, and

  3. Collisional properties of trapped cold chromium atoms

    CERN Document Server

    Pavlovich, Z; Côté, R; Sadeghpour, H R; Pavlovic, Zoran; Roos, Bjoern O.; Côté, Robin

    2004-01-01

    We report on calculations of the elastic cross section and thermalization rate for collision between two maximally spin-polarized chromium atoms in the cold and ultracold regimes, relevant to buffer-gas and magneto-optical cooling of chromium atoms. We calculate ab initio potential energy curves for Cr2 and the van der Waals coefficient C6, and construct interaction potentials between two colliding Cr atoms. We explore the effect of shape resonances on elastic cross section, and find that they dramatically affect the thermalization rate. Our calculated value for the s-wave scattering length is compared in magnitude with a recent measurement at ultracold temperatures.

  4. Alloyed steel

    International Nuclear Information System (INIS)

    The composition and properties are listed of alloyed steel for use in the manufacture of steam generators, collectors, spacers, emergency tanks, and other components of nuclear power plants. The steel consists of 0.08 to 0.11% w.w. C, 0.6 to 1.4% w.w. Mn, 0.35 to 0.6% w.w. Mo, 0.02 to 0.07% w.w. Al, 0.17 to 0.37% w.w. Si, 1.7 to 2.7% w.w. Ni, 0.03 to 0.07% w.w. V, 0.005 to 0.012% w.w. N, and the rest is Fe. The said steel showed a sufficiently low transition temperature between brittle and tough structures, a greater depth of hardenability, and better weldability than similar steels. (B.S.)

  5. Mitigation of Hexavalent Chromium in Storm Water Resulting from Demolition of Large Concrete Structure at the East Tennessee Technology Park - 12286

    Energy Technology Data Exchange (ETDEWEB)

    Britto, Ronnie; Brown, Bridget; Hale, Timothy B.; Hensley, Janice L.; Johnson, Robert T.; Patel, Madhu [Tetra Tech, Inc. (United States); Emery, Jerry A. [Energy Solutions, Inc. (United States); Gaston, Clyde [LATA-SHARP Remediation Services - LSRS (United States); Queen, David C. [U.S. DOE-ORO (United States)

    2012-07-01

    American Recovery and Reinvestment Act (ARRA) funding was provided to supplement the environmental management program at several DOE sites, including the East Tennessee Technology Park (ETTP) in Oak Ridge, Tennessee. Demolition of the ETTP K-33 Building, the largest building to be demolished to date in Oak Ridge, was awarded to LSRS in FY-2010 under the ARRA program. The K-33 building was an 82 foot tall 2-story structure covering approximately 32 acres. Once this massive building was brought down to the ground, the debris was segregated and consolidated into piles of concrete rubble and steel across the remaining pad. The process of demolishing the building, tracking across concrete debris with heavy equipment, and stockpiling the concrete rubble caused it to become pulverized. During and after storm events, hexavalent chromium leached from the residual cement present in the large quantities of concrete. Storm water control measures were present to preclude migration of contaminants off-site, but these control measures were not designed to control hexavalent chromium dissolved in storm water from reaching nearby receiving water. The following was implemented to mitigate hexavalent chromium in storm water: - Steel wool was distributed around K-33 site catch basins and in water pools as an initial step in addressing hexavalent chromium. - Since the piles of concrete were too massive and unsafe to tarp, they were placed into windrows in an effort to reduce total surface area. - A Hach colorimetric field meter was acquired by the K-33 project to provide realtime results of hexavalent chromium in site surface water. - Three hexavalent chromium treatment systems were installed at three separate catch basins that receive integrated storm water flow from the K-33 site. Sodium bisulfite is being used as a reducing agent for the immobilization of hexavalent chromium while also assisting in lowering pH. Concentrations initially were 310 - 474 ppb of hexavalent chromium in

  6. Steel welding.

    OpenAIRE

    Kučera, Marek

    2011-01-01

    Topic of the thesis concerns the problem of steel welding. The aim was to give acomprehensive overview on the topic, describe the known methods, advantages and disadvantages of welding technology. The introductory part is focused on introducing the basics of the process required to produce high-quality connections. Chapter three offers an overview of known and used welding methods with thein brief description of the method. The next chapter describes steel as material suitable for welding....

  7. Evaluation of stainless steels for their resistance to intergranular corrosion

    International Nuclear Information System (INIS)

    Austenitic stainless steels are being considered as structural materials for first wall/blanket systems in the international thermonuclear reactor (ITER). The uniform corrosion of stainless steels in water is well known and is not a critical issue limiting its application for the ITER design. The sensitivity of austenitic steels to intergranular corrosion (IGC) can be estimated rather accurately by means of calculation methods, considering structure and chemical composition of steel. There is a maximum permissible carbon content level, at which sensitization of stainless steel is eliminated: K=Creff-αCeff, where α-thermodynamic coefficient, Creff-effective chromium content (regarding molybdenum influence) and Ceff-effective carbon content (taking into account nickel and stabilizing elements). Corrosion tests for 16Cr11Ni3MoTi, 316L and 316LN steel specimens, irradiated up to 2 x 1022 n/cm2 fluence have proved the effectiveness of this calculation technique for determination of austenitic steels tendency to IGC. This method is directly applicable in austenitic stainless steel production and enables one to exclude complicated experiments on determination of stainless steel susceptibility to IGC. (orig.)

  8. Interaction of screw and edge dislocations with chromium precipitates in ferritic iron: An atomistic study

    International Nuclear Information System (INIS)

    Binary (Fe, Cr) alloys and high-chromium ferritic-martensitic steels undergo α-α' phase separation under thermal ageing or irradiation. The resulting Cr-rich precipitates (α' phase) are well known to cause hardening and embrittlement in such alloys and steels. In this work molecular statics (MS) and molecular dynamics (MD) simulations were applied to study the interaction between both a 1/2 screw and 1/2{1 1 0} edge dislocation with pure Cr precipitates in a bcc Fe matrix at various temperatures. After summarizing the interaction mechanisms for both types of dislocations, an analytical assessment of the interaction energy between a dislocation and precipitate is presented. The critical stress derived from the interaction energy is compared with MD data to reveal a possible correlation. For the edge dislocation and a precipitate of diameter less than 4 nm correlation with MD data is good, while for the screw dislocation no correlation was found.

  9. An in vitro comparison of nickel and chromium release from brackets

    Directory of Open Access Journals (Sweden)

    Ana Cristina Soares Santos Haddad

    2009-12-01

    Full Text Available This study aimed at comparing amounts of nickel (Ni and chromium (Cr released from brackets from different manufacturers in simulated oral environments. 280 brackets were equally divided into 7 groups according to manufacturer. 6 groups of brackets were stainless steel, and 1 group of brackets was made of a cobalt-chromium alloy with low Ni content (0.5%. International standard ISO 10271/2001 was applied to provide test methods. Each bracket was immersed in 0.5 ml of synthetic saliva (SS or artificial plaque fluid (PF over a period of 28 days at 37ºC. Solutions were replaced every 7 days, and were analyzed by spectrometry. The Kruskal-Wallis test was applied. Amounts of Ni release in SS (µg L-1 per week varied between groups from "bellow detection limits" to 694, and from 49 to 5,948.5 in PF. The group of brackets made of cobalt-chromium alloy, with the least nickel content, did not release the least amounts of Ni. Amounts of Cr detected in SS and in PF (µg L-1 per week were from 1 to 10.4 and from 50.5 to 8,225, respectively. It was therefore concluded that brackets from different manufacturers present different corrosion behavior. Further studies are necessary to determine clinical implications of the findings.

  10. Surface hardening of steels by alloying under laser heating with subsequent chemical thermal treatment

    International Nuclear Information System (INIS)

    The combination of laser alloying of carbon and low-chromium steels (20, 40, 45, 20Kh and 40Kh) with nitride-forming elements (V, Cr, Mo, Al) and subsequent nitriding is under consideration as a promising technology of enhancing wear resistance of steels. It is shown that the technology proposed permits increasing microhardness, wear resistance and favourable distribution of residual stresses in surface layers

  11. Optimization of Processing Parameters in ECM of Die Tool Steel Using Nanofluid by Multiobjective Genetic Algorithm

    OpenAIRE

    V. Sathiyamoorthy; T. Sekar; Elango, N

    2015-01-01

    Formation of spikes prevents achievement of the better material removal rate (MRR) and surface finish while using plain NaNO3 aqueous electrolyte in electrochemical machining (ECM) of die tool steel. Hence this research work attempts to minimize the formation of spikes in the selected workpiece of high carbon high chromium die tool steel using copper nanoparticles suspended in NaNO3 aqueous electrolyte, that is, nanofluid. The selected influencing parameters are applied voltage and electrolyt...

  12. Molybdenum effect on the properties of high-strength stainless steels type 14Cr-6Ni

    International Nuclear Information System (INIS)

    Molybdenum effect on the physicochemical properties and microstructure of 07Kh14N6 steel welded specimens has been investigated. The relationship is shown of deterioration of strength properties and stress corrosion resistance of stainless martensitic steels with grain boundaries state (presence of carbide) network) and matrix decomposition into two types of solid solutions - enriched and leaned by chromium. The role of molybdenum in improvement of these properties is pointed out

  13. Metal release from stainless steels and the pure metals in different media

    OpenAIRE

    Herting, Gunilla

    2004-01-01

    This study has been triggered by the fact that stainless steel is being increasingly used in new applications, where possible environmental effects may be a matter of concern. When stainless steel is exposed to a given environment, a key issue is the release of small amounts of the main alloying elements iron, chromium, nickel and molybdenum. Published release rate data of these elements turned out to be sparse. Furthermore, only little was known about the role of different parameters that ma...

  14. Physical metallurgy of extra strength nitrogen stainless steels

    International Nuclear Information System (INIS)

    The optimal composition that ensures the necessary service characteristics of high strength austenitic nonmagnetic nitrogen stainless steels must contain at least 18% Mn, 18% Cr, and 0.6% N. Chromium significantly affects corrosion cracking, relaxation, and erosion resistance. For more complex alloys containing nickel, molybdenum, and niobium, chromium has a considerable effect on plasticity bending, which is caused by ability of the alloy to resist forge-rolling (rigid cold stretching) that is used for the achievement of a high yield limit. The technology of nitration under pressure in the process of electro slag remelting allows one to regulate the content of nitrogen which is much greater than the solubility of nitrogen in steels under ordinary conditions. Application of special recrystallizing (mechanical and thermal) treatment and strain strengthening of blanks by cold working suppresses the formation of coarse-grained structure and ensures fine grains of eight to none number. (author)

  15. Development of sintered Mn-(Mo)-(Cr)-C steels

    International Nuclear Information System (INIS)

    The potential of manganese and chromium as alloying elements, reflected in their widespread use in wrought medium-to-high strength steels, is still to be realised in powder metallurgy alloys. The attempts to sinter Mn [+ Cr] alloys have largely ended in failure, due to either poor mechanical properties or reproducibility. The authors have analysed previously published results and identified the principal reason as lack of process control: both the powder preparation and during sintering. This lead tp large-scale oxidation, in the form of brittle networks, and also to lack of diffusion, due to the oxide film barriers. Reviewed now are and necessary processing conditions established for the successful processing of manganese steels. The development of additional chromium and molybdenum alloying is also considered and results are presented with additionally incorporate current areas of research, involving warm compaction, high temperature (including liquid phase) sintering and sinter and air hardening. (author)

  16. 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.

  17. Current status and recent research achievements in ferritic/martensitic steels

    International Nuclear Information System (INIS)

    When the austenitic stainless steel 316L(N) was selected for ITER, it was well known that it would not be suitable for DEMO and fusion reactors due to its irradiation swelling at high doses. A parallel programme to ITER collaboration already had been put in place, under an IEA fusion materials implementing agreement for the development of a low activation ferritic/martensitic steel, known for their excellent high dose irradiation swelling resistance. After extensive screening tests on different compositions of Fe–Cr alloys, the chromium range was narrowed to 7–9% and the first RAFM was industrially produced in Japan (F82H: Fe–8%Cr–2%W–TaV). All IEA partners tested this steel and contributed to its maturity. In parallel several other RAFM steels were produced in other countries. From those experiences and also for improving neutron efficiency and corrosion resistance, European Union opted for a higher chromium lower tungsten grade, Fe–9%Cr–1%W–TaV steel (Eurofer), and in 1997 ordered the first industrial heats. Other industrial heats have been produced since and characterised in different states, including irradiated up to 80 dpa. China, India, Russia, Korea and US have also produced their grades of RAFM steels, contributing to overall maturity of these steels. This paper reviews the work done on RAFM steels by the fusion materials community over the past 30 years, in particular on the Eurofer steel and its design code qualification for RCC-MRx

  18. Current status and recent research achievements in ferritic/martensitic steels

    Science.gov (United States)

    Tavassoli, A.-A. F.; Diegele, E.; Lindau, R.; Luzginova, N.; Tanigawa, H.

    2014-12-01

    When the austenitic stainless steel 316L(N) was selected for ITER, it was well known that it would not be suitable for DEMO and fusion reactors due to its irradiation swelling at high doses. A parallel programme to ITER collaboration already had been put in place, under an IEA fusion materials implementing agreement for the development of a low activation ferritic/martensitic steel, known for their excellent high dose irradiation swelling resistance. After extensive screening tests on different compositions of Fe-Cr alloys, the chromium range was narrowed to 7-9% and the first RAFM was industrially produced in Japan (F82H: Fe-8%Cr-2%W-TaV). All IEA partners tested this steel and contributed to its maturity. In parallel several other RAFM steels were produced in other countries. From those experiences and also for improving neutron efficiency and corrosion resistance, European Union opted for a higher chromium lower tungsten grade, Fe-9%Cr-1%W-TaV steel (Eurofer), and in 1997 ordered the first industrial heats. Other industrial heats have been produced since and characterised in different states, including irradiated up to 80 dpa. China, India, Russia, Korea and US have also produced their grades of RAFM steels, contributing to overall maturity of these steels. This paper reviews the work done on RAFM steels by the fusion materials community over the past 30 years, in particular on the Eurofer steel and its design code qualification for RCC-MRx.

  19. Reduction of Hexavalent Chromium by Viable Cells of Chromium Resistant Bacteria Isolated from Chromite Mining Environment

    OpenAIRE

    Satarupa Dey; Baishali Pandit; A. K. Paul

    2014-01-01

    Environmental contamination of hexavalent chromium [Cr(VI)] is of serious concern for its toxicity as well as mutagenic and carcinogenic effects. Bacterial chromate reduction is a cost-effective technology for detoxification as well as removal of Cr(VI) from polluted environment. Chromium resistant and reducing bacteria, belonging to Arthrobacter, Pseudomonas, and Corynebacterium isolated from chromite mine overburden and seepage samples of Orissa, India, were found to tolerate 12–18 mM Cr(VI...

  20. Reduction of Chromium-VI by Chromium Resistant Lactobacilli: A Prospective Bacterium for Bioremediation

    OpenAIRE

    Mishra, Ritesh; Sinha, Vartika; Kannan, Ambrose; Upreti, Raj K.

    2012-01-01

    Chromium is a toxic heavy metal, which primarily exists in two inorganic forms, Cr (VI) and Cr (III). Highly soluble hexavalent chromium is carcinogenic due to its oxidizing nature. It is well established that the intestinal bacteria including Lactobacilli have regulatory effect on intestinal homeostasis and a breakdown in the relationship between intestinal cells and bacteria results in the manifestation of gastrointestinal (GI) disorders. In this study Cr (VI) resistance was developed in La...

  1. Mechanical properties of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    OpenAIRE

    Mirković Nemanja

    2007-01-01

    Background/Aim. Metal-ceramic bond strength and alloys' elastic modulus clearly determine the potential of alloy application, because the ceramic integrity during mastication depends on these two characteristics. The aim of this study was to evaluate metal-ceramic bond strength and elastic modulus of cobalt-chromium alloys in making porcelainfused- to-metal restorations, regarding the application of the most frequent nickel-chromium alloy. Methods. The research was performed as an experimenta...

  2. Stainless steel: Recovery of properties after exposure to detrimental phases

    OpenAIRE

    Skaare, Andreas

    2015-01-01

    High alloyed stainless steel provides a desirable combination of corrosion resistance and mechanical properties, being a preferred material when ductility, overall strength and resistance to harsh environments are required. High service temperatures where alloy elements, as chromium and molybdenum, are present, is a well-known recipe for the precipitation of detrimental phases in the material. Even a small amount of these precipitations may impair the mechanical and corrosion properties. T...

  3. Review on Pretreatment of Effluent Released from Steel Industry

    OpenAIRE

    Meena Vangalpati1

    2014-01-01

    There are many reasons for the environmental pollution.One of the main reason is the vast industrialization, which contributes to 78% of the world’s pollution.There are various industries like leather,food,automobile,pharmaceutical,leather,textile,etc,responsible for the destruction of nature. Steel is one of the major metal produced in huge quantities which releases toxic effluents like nickel,copper,cadmium,lead,nitrates,chromium .These elements lead to great destruction in ...

  4. Identification of scale formed on Cr-Ni cast steel

    Directory of Open Access Journals (Sweden)

    B. Kalandyk

    2010-10-01

    Full Text Available An attempt has been made to identify the scale formed on austenitic chromium-nickel cast steel with additions of Ti and Zr duringoxidising at temperatures of 820 and 1000 °C. The scale identification was done by the technique of scanning microscopy, by X-raydiffraction phase analysis in Bragg-Brentano geometry with constant angle of incidence, and by scratch test.

  5. Stabilization of final titanium concentration in stainless steel

    International Nuclear Information System (INIS)

    The technology of combined alloying of stainless steel type 08-12Kh18N10T with 30%-ferrotitanium and metallic spongy titanium is developed and put into practice. This permits to stabilize titanium assimilation at the level of 40-60 % in two-slag melting process and to increase chromium recovering from the slag. Stabilization of titanium assimilation promotes its homogeneous distribution in final metal after electroslag remelting. 2 refs. 3 figs

  6. Defect structure of electrodeposited chromium layers

    International Nuclear Information System (INIS)

    Positron annihilation spectroscopy was applied to study the effects of pre-treatment and composition of substrates on the quality and defect structure of electrodeposited thick chromium coatings. The results show that both parameters are important, and a scenario is proposed why the mechanically polished substrate gives more defective film than the electro polished one.

  7. Defect structure of electrodeposited chromium layers

    CERN Document Server

    Marek, T; Vertes, A; El-Sharif, M; McDougall, J; Chisolm, C U

    2000-01-01

    Positron annihilation spectroscopy was applied to study the effects of pre-treatment and composition of substrates on the quality and defect structure of electrodeposited thick chromium coatings. The results show that both parameters are important, and a scenario is proposed why the mechanically polished substrate gives more defective film than the electro polished one.

  8. Flashlamp-pumped lasing of chromium: GSGG

    International Nuclear Information System (INIS)

    Lasing action in chromium-doped gadolinium scandium gallium garnet (Cr:GSGG) is well established for both CW/sup (1)/ and flashlamp/sup (2)/ pumping. This paper describes an investigation of flashlamp-pumped Cr:GSGG lasers and indicates some of the factors which limit performance

  9. Trace Elements Excluding Iron - Chromium and Zinc

    Science.gov (United States)

    The percentage of middle-aged US adults who are participating in leisure-time physical activities is growing. These adults also seek credible information about specific supplements that the public press routinely describes as necessary to enable increases in physical performance. Chromium and zinc a...

  10. HEALTH ASSESSMENT DOCUMENT FOR CHROMIUM. FINAL REPORT

    Science.gov (United States)

    The full document represents a comprehensive data base that considers all sources of chromium in the environment, the likelihood for its exposure to humans, and the possible consequences to man and lower organisms from its absorption. This information is integrated into a format ...

  11. 29 CFR 1926.1126 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1926.51 Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1926.51. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  12. 29 CFR 1910.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1910.141. Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1910.141. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  13. 29 CFR 1915.1026 - Chromium (VI).

    Science.gov (United States)

    2010-07-01

    ... CFR 1910.141. Where skin contact with chromium (VI) occurs, the employer shall provide washing facilities in conformance with 29 CFR 1915.97. Eating and drinking areas provided by the employer shall also... requirements of the Hazard Communication Standard, 29 CFR 1910.1200. (3) Cleaning and replacement. (i)...

  14. Biological groundwater treatment for chromium removal at low hexavalent chromium concentrations.

    Science.gov (United States)

    Mamais, Daniel; Noutsopoulos, Constantinos; Kavallari, Ioanna; Nyktari, Eleni; Kaldis, Apostolos; Panousi, Eleni; Nikitopoulos, George; Antoniou, Kornilia; Nasioka, Maria

    2016-06-01

    The objective of this work is to develop and evaluate biological groundwater treatment systems that will achieve hexavalent chromium reduction and total chromium removal from groundwater at hexavalent chromium (Cr(VI)) groundwater concentrations in the 0-200 μg/L range. Three lab-scale units operated, as sequencing batch reactors (SBR) under aerobic, anaerobic and anaerobic-aerobic conditions. All systems received groundwater with a Cr(VI) content of 200 μg/L. In order to support biological growth, groundwater was supplemented with milk, liquid cheese whey or a mixture of sugar and milk to achieve a COD concentration of 200 mg/L. The results demonstrate that a fully anaerobic system or an anaerobic-aerobic system dosed with simple or complex external organic carbon sources can lead to practically complete Cr(VI) reduction to Cr(III). The temperature dependency of maximum Cr(VI) removal rates can be described by the Arrhenius relationship. Total chromium removal in the biological treatment systems was not complete because a significant portion of Cr(III) remained in solution. An integrated system comprising of an anaerobic SBR followed by a sand filter achieved more than 95% total chromium removal thus resulting in average effluent total and dissolved chromium concentrations of 7 μg/L and 3 μg/L, respectively. PMID:26971177

  15. Nephrotoxic and hepatotoxic effects of chromium compounds in rats

    Energy Technology Data Exchange (ETDEWEB)

    Laborda, R.; Diaz-Mayans, J.; Nunez, A.

    1986-03-01

    The nephrotoxic, hepatotoxic and cardiotoxic actions of hexavalent chromium compounds, as well as their effects on lung, blood and circulation may contribute to the fatal outcome of chromium intoxication. Although trivalent chromium have been regarded as relatively biologically inert, there are a few salts of chromium III that have been found to be carcinogenic when inhaled, ingested or brought in contact with the tissues. Sensitive persons and industry workers have been subjects of dermatitis, respiratory tract injuries and digestive ulcers due to chromium compounds. In this work, the authors have studied the effect of trivalent and hexavalent chromium compounds on rats measuring the transaminases (GOT and GPT), urea and creatinine levels in serum of chromium poisoned animals at different times.

  16. A Kinetic Model of Chromium in a Flame

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Chromium has been identified as a carcinogenic metal.Incineration is the useful method for disposal of toxic chromium hazard waste and a chromium kinetic model in a flame is very important to study chromium oxidation.Chromium chemical kinetics over a range of temperatures of a hydrogen/air flame is proposed.Nine chromium compounds and fifty-eight reversible chemical reactions were considered The forward reaction rates are calculated based on the molecular collision approach for unknown ones and Arrhenius's Law for known ones.The backward reaction rates were calculated according to forward reaction rates, the equilibrium constants and chemical thermodynamics.It is verified by several equilibrium cases and is tested by a hydrogen/air diffusion flame.The results show that the kinetic model could be used in cases in which the chromium kinetics play an important role in a flame

  17. The Chromium is an essential element in the human

    International Nuclear Information System (INIS)

    The Chromium is an essential element for human and animals, because it a preponderant function in the insulin metabolism as a glucose tolerance factor (GTF). The deficiency of chromium engenders a deterioration in the glucose metabolism due to bad efficiency of insulin. Because the importance of this element an exhaustive reference review was made and this presents some studies realized in laboratory animals and in human beings where it is prove with resuits the effect of chromium over the improvement of patients with non-insulin dependant diabetes. Three substances are presented as chromium active biological forms: a material rich in chromium known as glucose tolerance factor, chromium picolinate and a substance of low molecular weight LMWCr in its forms of apo and holo that contains chromium and it links the insulin receptor and improves its activity. Also this paper presents information about the condition of diabetes in Costa Rica. (Author)

  18. Crystallization of Low-alloyed Construction Cast Steel Modified with V and Ti

    Directory of Open Access Journals (Sweden)

    A. Studnicki

    2013-07-01

    Full Text Available In this paper crystallization studies of low-alloyed construction cast steel were presented for different additions of chromium, nickel and molybdenum modified with vanadium and titanium. Studies were conducted using developed TDA stand, which additionally enabled evaluation of cooling rate influence on crystallization process of investigated alloys.

  19. Male-mediated spontaneous abortion among spouses of stainless steel welders

    DEFF Research Database (Denmark)

    Hjollund, N H; Bonde, Jens Peter; Jensen, Tina Kold;

    2000-01-01

    Male-mediated spontaneous abortion has never been documented for humans. The welding of stainless steel is associated with the pulmonary absorption of hexavalent chromium, which has genotoxic effects on germ cells in rodents. Clinical and early subclinical spontaneous abortions were examined among...

  20. Serum Chrome levels sampled with steel needle vs. plastic IV cannula

    DEFF Research Database (Denmark)

    Penny, Jeannette Østergaard; Overgaard, Søren

    2010-01-01

      Modern Metal-on-metal (MoM) joint articulations releases metal ions to the body. Research tries to establish how much this elevates metal ion levels and whether it causes adverse effects. The steel needle that samples the blood may introduce additional chromium to the sample thereby causing bia...

  1. In situ Raman identification of stainless steels pitting corrosion films

    International Nuclear Information System (INIS)

    Raman spectroscopy is used for the in situ identification of the corrosion products grown during the pitting corrosion of stainless steels in presence of NaCl. To obtain a better approach of these complicated materials, binary alloys are first investigated, in which the alloying element is present in the same ratio as in steel. Here, results on Fe-10%Ni and Fe-18%Cr, AISI304 and AISI316 are presented and the respective parts played by chromium and molybdenum in the prevention of pitting corrosion are described. The outer product, ''colloidal'' green rust (GR) ,is particularly studied and a GR formula is proposed

  2. Thermodynamic Modeling as a Strategy for Casting High Alloy Steels

    Institute of Scientific and Technical Information of China (English)

    Peri Reddy V; S Raman Sankaranarayanan

    2009-01-01

    Strategies based on thermodynamic calculations can be used to overcome the problems associated with oxides encountered in steel plant operations, which can lead to certain difficulties in the process such as clogging of submerged entry nozzle during continuous casting. Approaches to producing high alloy steels by continuous casting have been taken. One of the strategies to avoid the oxidation of chromium is to add a small amount of other elements (subject to other constraints), which do not cause subsequent problems. The problem has been studied using the Thermo-CalcR software, with related databases; and the results obtained for different process conditions or generic com-positions have been presented.

  3. Processing of steel containing metallic elements, especially cobalt and/or nickel for their elimination from the steel

    International Nuclear Information System (INIS)

    The melted steel is contacted with a prepared slag 1 for chromium oxidation a slag 2 and a metallic alloy A are obtained, they are separated by decantation. The alloy A is oxidized by gaseous oxygen, a slag 3 and an alloy B are obtained. Alloy B has a high Co and/or Ni content and is separated from the slag 3 by decantation

  4. Reaction of chromium(VI) with glutathione or with hydrogen peroxide: identification of reactive intermediates and their role in chromium(VI)-induced DNA damage.

    OpenAIRE

    Aiyar, J; Berkovits, H J; Floyd, R A; Wetterhahn, K E

    1991-01-01

    The types of reactive intermediates generated upon reduction of chromium(VI) by glutathione or hydrogen peroxide and the resulting DNA damage have been determined. In vitro, reaction of chromium(VI) with glutathione led to formation of two chromium(V) complexes and the glutathione thiyl radical. When chromium(VI) was reacted with DNA in the presence of glutathione, chromium-DNA adducts were obtained, with no DNA strand breakage. The level of chromium-DNA adduct formation correlated with chrom...

  5. Design and performance of chromium mist generator

    Directory of Open Access Journals (Sweden)

    Tirgar Aram

    2006-01-01

    Full Text Available Chromium mist generator is an essential tool for conducting researches and making science-based recommendations to evaluate air pollution and its control systems. The purpose of this research was to design and construct a homogenous chromium mist generator and the study of some effective factors including sampling height and distances between samplers in side-by-side sampling on chromium mist sampling method. A mist generator was constructed, using a chromium electroplating bath in pilot scale. Concentration of CrO3 and sulfuric acid in plating solution was 125 g L-1 and 1.25 g L-1, respectively. In order to create permanent air sampling locations, a Plexiglas cylindrical chamber (75 cm height, 55 cm i.d was installed the bath overhead. Sixty holes were produced on the chamber in 3 rows (each 20. The distance between rows and holes was 15 and 7.5 cm, respectively. Homogeneity and effective factors were studied via side-by-side air sampling method. So, 48 clusters of samples were collected on polyvinyl chloride (PVC filters housed in sampling cassettes. Cassettes were located in 35, 50, and 65 cm above the solution surface with less than 7.5 and/or 7.5-15 cm distance between heads. All samples were analyzed according to the NIOSH method 7600. According to the ANOVA test, no significant differences were observed between different sampling locations in side-by-side sampling (P=0.82 and between sampling heights and different samplers distances (P=0.86 and 0.86, respectively. However, there were notable differences between means of coefficient of variations (CV in various heights and distances. It is concluded that the most chromium mist homogeneity could be obtained at height 50 cm from the bath solution surface and samplers distance of < 7.5 cm.

  6. Liquid Phase Sintering of Highly Alloyed Stainless Steel

    DEFF Research Database (Denmark)

    Mathiesen, Troels

    1996-01-01

    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......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 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...

  7. Development of oxide dispersion strengthened 2205 duplex stainless steel composite

    Directory of Open Access Journals (Sweden)

    Oladayo OLANIRAN

    2015-05-01

    Full Text Available Composites of duplex stainless steel were produced by oxide dispersion strengthening with comparatively improved mechanical properties by hot press sintering of partially stabilized Zirconia (PSZ, 3% yttria, mole fraction dispersion in 2205 duplex stainless steels. Ceramic oxide was added as reinforcement, while chromium (Cr and Nickel (Ni were incorporated to maintain the austenitic/ferritic phase balance of the duplex stainless steel. The powders and sintered were characterized in detail using scanning electron microscopy (SEM and X-ray diffraction (XRD. The microstructural evolution and phase formation during oxide dispersion strengthening of duplex stainless steel composites were investigated. The influence of composition variation of the reinforcements on the microstructural and corrosion behaviour in simulated mine water of the composites were investigated. In this manuscript, it was established that composition has great influence on the structure/properties relationship of the composites developed.

  8. Surface reactions of tellurium on steel and zircaloy 4

    International Nuclear Information System (INIS)

    The reaction between tellurium vapours and 316 stainless steel and zircaloy 4 surfaces has been studied in the temperature range of 823-1223 K and 923-1273 K respectively. The reaction product, thickness and the intergranular attack penetration was measured for the reaction of tellurium in 316 stainless steel. In the case of zircaloy 4 reaction product was brittle and scooped out. Hence the thickness of the individual bands could not be measured. It was observed that the reaction of tellurium on 316 stainless steel and zircaloy 4 resulted in the formation of two bands in both the cases. In the case of 316 stainless steel-tellurium reaction, the outer band was rich in iron and nickel while the inner band was rich in chromium, whereas in the case of zircaloy 4-tellurium, the outer band was rich in zirconium and the inner band contained tin in addition to zirconium. Tellurium was found in both the bands. (auth.)

  9. 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.

  10. Inflence of S and Mn on ICC susceptibility of 02Kh18N13 steel in nitric acid media

    International Nuclear Information System (INIS)

    The paper studies the impact of S and Mn additions on grain boundary stability of annealed and tempered samples of 02Kh18N13 steel in nitric acid media with additions and without ions of hexavalent chromium. A negative impact of the medium and manganese is established for annealed samples which were tempered at 600 deg C for more than 50 h. This effect is presimably related to grain boundary segreagation of sulphur and manganese and accelerating impact of these elements on chromium deplition of the boundaries of sensitized steel grains

  11. Chromium vaporization from mechanically deformed pre-coated interconnects in Solid Oxide Fuel Cells

    Science.gov (United States)

    Falk-Windisch, Hannes; Sattari, Mohammad; Svensson, Jan-Erik; Froitzheim, Jan

    2015-11-01

    Cathode poisoning, associated with Cr evaporation from interconnect material, is one of the most important degradation mechanisms in Solid Oxide Fuel Cells when Cr2O3-forming steels are used as the interconnect material. Coating these steels with a thin Co layer has proven to decrease Cr vaporization. To reduce production costs, it is suggested that thin metallic PVD coatings be applied to each steel strip before pressing the material into interconnect shape. This process would enable high volume production without the need for an extra post-coating step. However, when the pre-coated material is mechanically deformed, cracks may form and lower the quality of the coating. In the present study, Chromium volatilization is measured in an air-3% H2O environment at 850 °C for 336 h. Three materials coated with 600 nm Co are investigated and compared to an uncoated material. The effect of deformation is investigated on real interconnects. Microscopy observations reveal the presence of cracks in the order of several μm on the deformed pre-coated steel. However, upon exposure, the cracks can heal and form a continuous surface oxide rich in Co and Mn. As an effect of the rapid healing, no increase in Cr vaporization is measured for the pre-coated material.

  12. Development status und future possibilities for martensitic creep resistant steels

    Energy Technology Data Exchange (ETDEWEB)

    Hald, J. [Technical Univ. Denmark, Lyngby (Denmark). Dept. of Mechanical Engineering

    2010-07-01

    In the last four decades new stronger modified 9%Cr martensitic creep resistant steels have been introduced in power plants, which has enabled increases in maximum achievable steam conditions from the previous 250 bar and 540-560 C up to the values of 300 bar and 600-620 C currently being introduced all over the world. In order to further increase the steam parameters of steel based power plants up to a target value of 650 C/325 bar it is necessary to double the creep strength of the martensitic steels. At the same time the resistance against steam oxidation must be improved by an increase of the chromium content in the steels from 9% to 12%. However, so far all attempts to make stronger 12%Cr steels have led to breakdowns in long-term creep strength. Significant progress has been achieved in the understanding of microstructure stability of the martensitic 9-12%Cr steels: Observed microstructure instabilities in 11-12%Cr steels are explained by Z-phase precipitation, which dissolves fine MN nitrides. Improved understanding of effects of B and N on long-term creep properties has formed the basis of a series of new stronger 9%Cr test alloys with improved creep strength. In parallel 9%Cr test steels with low C content show very promising behavior in long-term tests. However, the 9%Cr steels must be surface coated to protect against steam oxidation at high temperature applications above 620%C. A possibility to use fine Z-phases for strengthening of the martensitic steels has been identified, and this opens a new pathway for development of stable strong 12%Cr steels. There are still good prospects for the realization of a 325 bar / 650 C steam power plant all based on steel. (orig.)

  13. Thermomechanically-controlled Processing for Producing Ship-building Steels

    Directory of Open Access Journals (Sweden)

    B. Basu

    2005-01-01

    Full Text Available The thermomechanically-controlled processing of a newly developed high-strength lowalloy steel has been designed in such a way that the problems, normally faced in producing thequench and tempered steels, have been mitigated and the final product (steel plates are available in as rolled condition rather than quench and tempered steels.A low-carbon, low-alloy steel having nickel, chromium, copper, niobium, boron, has been designed for ease of welding, improved weldability over the conventional steels, and responsiveto the thermomechanically-controlled processing. A number of laboratory-scale batches of the alloy were made with different combinations of thermomechanically-controlled processingparameters. The different thermomechanically-controlled processing parameters studied include (i slab-reheating temperature,~ (ii. def.orm ation above recrvstallisation temperature, (iiideformation below recrystallisation temperature, and (iv finish-rolling temperature. The thermomechanically-processed steel plates, under certain combinations of  thermomechanically-controlled ~rocessi-ne.o arameters. showed excellent combination of imvact and tensile n.r on. erties. In this paper, the microstructure-property correlation has been made to throw light on the type of microstructure required to obtain such superior package of mechanical properties. Further, the optimised laboratory-scale thermomechanically-controlled processing parameters, which were used to process newer hatches of the steel made through industrial route, have delivered encouraging results.

  14. Chromium supplementation improved post-stroke brain infarction and hyperglycemia.

    Science.gov (United States)

    Chen, Wen-Ying; Mao, Frank Chiahung; Liu, Chia-Hsin; Kuan, Yu-Hsiang; Lai, Nai-Wei; Wu, Chih-Cheng; Chen, Chun-Jung

    2016-04-01

    Hyperglycemia is common after acute stroke and is associated with a worse outcome of stroke. Thus, a better understanding of stress hyperglycemia is helpful to the prevention and therapeutic treatment of stroke. Chromium is an essential nutrient required for optimal insulin activity and normal carbohydrate and lipid metabolism. Beyond its nutritional effects, dietary supplement of chromium causes beneficial outcomes against several diseases, in particular diabetes-associated complications. In this study, we investigated whether post-stroke hyperglycemia involved chromium dynamic mobilization in a rat model of permanent focal cerebral ischemia and whether dietary supplement of chromium improved post-stroke injury and alterations. Stroke rats developed brain infarction, hyperglycemia, hyperinsulinemia, glucose intolerance, and insulin resistance. Post-stroke hyperglycemia was accompanied by elevated secretion of counter-regulatory hormones including glucagon, corticosterone, and norepinephrine, decreased insulin signaling in skeletal muscles, and increased hepatic gluconeogenesis. Correlation studies revealed that counter-regulatory hormone secretion showed a positive correlation with chromium loss and blood glucose increased together with chromium loss. Daily chromium supplementation increased tissue chromium levels, attenuated brain infarction, improved hyperglycemia, and decreased plasma levels of glucagon and corticosterone in stroke rats. Our findings suggest that stroke rats show disturbance of tissue chromium homeostasis with a net loss through urinary excretion and chromium mobilization and loss might be an alternative mechanism responsible for post-stroke hyperglycemia. PMID:26477944

  15. The CCT diagrams of ultra low carbon bainitic steels and their impact toughness properties

    International Nuclear Information System (INIS)

    The CCT diagrams of ULCBNi steels, HN3MV, HN3MVCu having 5.1% Ni and 3.5% Ni and Cu bearing steels; HN3M1.5Cu, HSLA 100 have been determined. The reduced carbon concentration in steel, in order to prevent the formation of cementite, allowed for using nickel, manganese, chromium and molybdenum to enhance hardenability and refinement of the bainitic microstructures by lowering BS temperature. Copper and microadditions of vanadium and niobium are successfully used for precipitation strengthening of steel both in thermomechanically or heat treated conditions. Very good fracture toughness at low temperatures and high yield strength properties of HN3MVCu and HN3MV steels allowed for fulfillment of the requirements for steel plates for pressure vessels and cryogenic applications. (author)

  16. Fatigue behavior of functionally graded steel produced by electro-slag remelting

    International Nuclear Information System (INIS)

    The present study attempts to investigate the fatigue behavior of functionally graded steel (FGS) produced through electroslag remelting (ESR) process. To produce FGSs, two different slices of plain carbon steel and austenitic stainless steel were welded and used as ESR's electrode. Some of alloying elements in austenitic stainless steel, such as Nickel and Chromium, as well as carbon in plain carbon steel may be replaced during remelting stage; graded layers (austenite and martensite layers) may also be fabricated. Vickers micro-hardness test and scanning electron microscopy (SEM) of FGS were performed and variations in hardness and microstructure were observed. SEM images exhibited multi-phase graded steel. The rotating bending fatigue test was performed on specimens. The fatigue test results showed improvement in fatigue limit of FGS in comparison with that of its ingredients. SEM's images of fatigue fracture surfaces in FGS showed deviation and branching in crack propagation when crack propagates from graded austenite to graded martensite phase

  17. ADHESION STRENGTH OF TiN COATINGS AT VARIOUS ION ETCHING DEPOSITED ON TOOL STEELS USING CATHODIC ARC PVD TECHNIQUE

    OpenAIRE

    MUBARAK ALI; ESAH HAMZAH; NOUMAN ALI

    2009-01-01

    Titanium nitride (TiN) widely used as hard coating material was coated on tool steels, namely on high-speed steel (HSS) and D2 tool steel by physical vapor deposition method. The goal of this study was to examine the effect of ion etching with and without titanium (Ti) and chromium (Cr) on the adhesion strength of TiN coatings deposited on tool steels. From the scratch tester, it was observed that by increasing Ti ion etching showed an increase in adhesion strength of the deposited coatings. ...

  18. Method and equipment for measurement of residual stresses in erection welded butts of pipelines made of clad steel

    International Nuclear Information System (INIS)

    Investigations into determination of residual stresses on welded joints of pipelines of 34 mm thick 22 K pearlitic steel cladded with a 4 mm thick layer of chromium-nickel steel are conducted under mounting at the Kursk NPP. Mounting welded joints of the pipelines of clad steel are under the effect of residual stresses, particularly, joints of tube-knee type, where the level of residual stresses reaches 450-550 MPa. Repair of mounting welded joints of pipeles of clad steel is stated to result in increase of residual stresses on the surface of the joints

  19. Hegelian Steel

    DEFF Research Database (Denmark)

    Kjær, Poul F.

    2015-01-01

    Even in our globalized world the notion of national economies remain incredibly strong, just as a considerable part of the literature on transnational governance and globalization continue to rely on a zero-sum perspective concerning the relationship between the national and the transnational. De...... of the European steel industry....

  20. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    Energy Technology Data Exchange (ETDEWEB)

    Kotsedi, L., E-mail: Kotsedi@tlabs.ac.za [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Nuru, Z.Y. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Mthunzi, P. [National Laser Centre, Council for Scientific and Industrial Research, 0001 Pretoria (South Africa); Muller, T.F.G. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Eaton, S.M. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Julies, B. [University of the Western Cape, Physics Department, Bellville, 7535 Cape Town (South Africa); Manikandan, E. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa); Ramponi, R. [Physics Department, Politecnico di Milano, Piazza Leonardo Da Vinci, 32, 20133 Milano (Italy); Maaza, M. [UNESCO-UNISA Africa Chair in Nanosciences-Nanotechnology, College of Graduate Studies, University of South Africa, Muckleneuk Ridge, P.O. Box 392, Pretoria (South Africa); Nanosciences African Network (NANOAFNET), iThemba LABS-National Research Foundation, 1 Old Faure Road, Somerset West 7129, P.O. Box 722, Somerset West, Western Cape (South Africa)

    2014-12-01

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr{sub 2}O{sub 3} layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr{sub 2}O{sub 3} layer. The α-Cr{sub 2}O{sub 3} layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%.

  1. Femtosecond laser surface structuring and oxidation of chromium thin coatings: Black chromium

    International Nuclear Information System (INIS)

    Highlights: • Oxidation of the chromium thin film to chromium oxide by femtosecond laser with a fundamental wavelength of 1064 nm. • Solar absorber from chromium oxide that low percentage reflectance. • Femtosecond laser oxidation, with a de-focused laser. • Chromium oxide formation by femtosecond laser in normal ambient. - Abstract: In view of their potential applications as selective solar absorbers, chromium coatings on float glass substrates were nano/micro structured by femtosecond laser in air. Raman and X-rays diffraction investigations confirmed the formation of an ultra-porous α-Cr2O3 layer at the surface; higher is the input laser power, enhanced is the crystallinity of the α-Cr2O3 layer. The α-Cr2O3 layer with the Cr underneath it in addition to the photo-induced porosity acted as a classical ceramic–metal nano-composite making the reflectance to decrease significantly within the spectral range of 190–1100 nm. The average reflectance decreased from 70 to 2%

  2. Production of basic chromium sulfate by using recovered chromium from ashes of thermally treated leather.

    Science.gov (United States)

    Dettmer, Aline; Nunes, Keila Guerra Pacheco; Gutterres, Mariliz; Marcílio, Nilson Romeu

    2010-04-15

    Leather wastes tanned with chromium are generated during the production process of leather, hence the wastes from hand crafted goods and footwear industries are a serious environmental problem. The thermal treatment of leather wastes can be one of the treatment options because the wastes are rich in chromium and can be used as a raw material for sodium chromate production and further to obtain several chromium compounds. The objective of this study was to utilize the chromium from leather wastes via basic chromium sulfate production to be subsequently applied in a hide tanning. The obtained results have shown that this is the first successful attempt to achieve desired base properties of the product. The result was achieved when the following conditions were applied: a molar ratio between sodium sulfite and sodium dichromate equal to 6; reaction time equal to 5 min before addition of sulfuric acid; pH of sodium dichromate solution equal to 2. Summarizing, there is an opportunity to utilize the dangerous wastes and reused them in the production scheme by minimizing or annulling the environmental impact and to attend a sustainable process development concept. PMID:20031309

  3. Evaluation of Nickel and Chromium Ion Release During Fixed Orthodontic Treatment Using Inductively Coupled Plasma-Mass Spectrometer: An In Vivo Study

    Science.gov (United States)

    Nayak, Rabindra S; Khanna, Bharti; Pasha, Azam; Vinay, K; Narayan, Anjali; Chaitra, K

    2015-01-01

    Background: Fixed orthodontic appliances with the use of stainless steel brackets and archwires made of nitinol have a corrosive potential in the oral environment. Nickel and chromium ions released from these appliances act as allergens apart from being cytotoxic, mutagenic and carcinogenic in smaller quantities in the range of nanograms. This study was done to evaluate the release of nickel and chromium ions from orthodontic appliances in the oral cavity using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). Materials and Methods: Saliva samples from 30 orthodontic patients undergoing treatment with 0.022″ MBT mechanotherapy were collected prior to commencement of treatment, after initial aligning wires and after 10-12 months of treatment. Salivary nickel and chromium ion concentration was measured in parts per billion (ppb) using ICP-MS. Results: Mean, standard deviation and range were computed for the concentrations of ions obtained. Results analyzed using ANOVA indicated a statistically significant increase of 10.35 ppb in nickel ion concentration and 33.53 ppb in chromium ion concentration after initial alignment. The ionic concentration at the end of 10-12 months of treatment showed a statistically significant increase in of 17.92 ppb for chromium and a statistically insignificant decrease in nickel ion concentration by 1.58 ppb. Pearson’s correlation coefficient showed a positive correlation for an increase in nickel concentration after aligning, but not at the end of 10-12 months. A positive correlation was seen for an increase in chromium ion concentration at both time intervals. Conclusion: Nickel and chromium ion concentration in saliva even though below the recommended daily allowance should not be ignored in light of the new knowledge regarding effects of these ions at the molecular level and the allergic potential. Careful and detailed medical history of allergy is essential. Nickel free alternatives should form an essential part of an

  4. Carburization of stainless steel furnace tubes

    International Nuclear Information System (INIS)

    Stainless steel containing molybdenum are usually recommended to resist naphtenic acid corrosion in vacuum heaters. In 1993 the original 5Cr-1/2Mo roof tubes of the furnace in a vacuum unit were replaced by stainless steel 316 Ti to minimize tube replacement and increase heater reliability. Unexpectedly, some of the new tubes failed after only three years of service and just one year after undergoing the last inspection. The damage occurred in the form of deep holes and perforations, starting from the outside tube surface on the fireside. Coke build-up occurred due to severe operating conditions, overheating the tubes on the fireside, above 675 Centigrade. Metallographic and Scanning Electron Microscopy (Sem) examination revealed internal and external carburization of the material due to the presence of coke and combustion ashes, respectively. The increase in the skin metal temperature facilitated the diffusion of carbon from these carbon-rich deposits into the low carbon content material (0.023%). Depletion of chromium at the grain boundaries due to the massive formation of chromium carbides, resulted in a severe intergranular corrosion attack by molten salts rich in vanadium and sulfur produced by asphalt burning. Normal operating practice demands the use of steam for the heater tubes to control coke build-up. This practice had been first reduced and then eliminated, during the past two years prior to the failure, because of economic incentives. This paper describes the root cause analysis conducted to account for these premature tube failures. (Author)

  5. Inelastic Scattering of Neutrons in Chromium

    International Nuclear Information System (INIS)

    The phonon spectrum of chromium has been studied by neutron inelastic scattering. The dispersion curves are very similar, in form to those of tungsten and molybdenum, indicating similar interionic force constants. The neutron groups broaden but do not shift appreciably when the temperature is raised. No effect has been observed which can be attributed to the interaction between the phonons and the crystal magnetization in the antiferromagnetic phase. (author)

  6. Observational Approach to Chromium Site Remediation - 13266

    International Nuclear Information System (INIS)

    Production reactors at the U.S. Department of Energy's (DOE) Hanford Site in Richland, Washington, required massive quantities of water for reactor cooling and material processing. To reduce corrosion and the build-up of scale in pipelines and cooling systems, sodium dichromate was added to the water feedstock. Spills and other releases at the makeup facilities, as well as leaks from miles of pipelines, have led to numerous areas with chromium-contaminated soil and groundwater, threatening fish populations in the nearby Columbia River. Pump-and-treat systems have been installed to remove chromium from the groundwater, but significant contamination remain in the soil column and poses a continuing threat to groundwater and the Columbia River. Washington Closure Hanford, DOE, and regulators are working on a team approach that implements the observational approach, a strategy for effectively dealing with the uncertainties inherent in subsurface conditions. Remediation of large, complex waste sites at a federal facility is a daunting effort. It is particularly difficult to perform the work in an environment of rapid response to changing field and contamination conditions. The observational approach, developed by geotechnical engineers to accommodate the inherent uncertainties in subsurface conditions, is a powerful and appropriate method for site remediation. It offers a structured means of quickly moving into full remediation and responding to the variations and changing conditions inherent in waste site cleanups. A number of significant factors, however, complicate the application of the observational approach for chromium site remediation. Conceptual models of contamination and site conditions are difficult to establish and get consensus on. Mid-stream revisions to the design of large excavations are time-consuming and costly. And regulatory constraints and contract performance incentives can be impediments to the flexible responses required under the observational

  7. Loading chromium atoms in a magnetic guide

    OpenAIRE

    Greiner, A; Sebastian, J.; Rehme, P.; Aghajani-Talesh, A.; Griesmaier, A.; Pfau, T.

    2007-01-01

    We have realized a magnetic guide for ultracold chromium atoms by continuously loading atoms directly from a Zeeman slower into a horizontal guide. We observe an atomic flux of $2 \\cdot 10^7$ atoms/s and are able to control the mean velocity of the guided atoms between 0 m/s and 3 m/s. We present our experimental results on loading and controlling the mean velocity of the guided atoms and discuss the experimental techniques that are used.

  8. X-616 Chromium Sludge Lagoons pictorial overview, Piketon, Ohio

    International Nuclear Information System (INIS)

    The Portsmouth Gaseous Diffusion Plant uses large quantities of water for process cooling. The X-616 Liquid Effluent Control Facility was placed in operation in December 1976 to treat recirculation cooling water blowdown from the process cooling system. A chromium-based corrosion inhibitor was used in the cooling water system. A chromium sludge was produced in a clarifier to control chromium levels in the water. Chromium sludge produced by this process was stored in two surface impoundments called the X-616 Chromium Sludge Lagoons. The sludge was toxic due to its chromium concentration and therefore required treatment. The sludge was treated, turning it into a sanitary waste, and buried in an Ohio EPA approved landfill. The plant's process cooling water system has changed to a more environmentally acceptable phosphate-based inhibitor. Closure activities at X-616 began in August 1990, with all construction activities completed in June 1991, at a total cost of $8.0 million

  9. Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

    Science.gov (United States)

    Adhe, K. M.; Kain, V.; Madangopal, K.; Gadiyar, H. S.

    1996-08-01

    Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination of mechanical and corrosion resistance properties. However, heat treatments can lower the mechanical strength of these stainless steels as well as render them susceptible to intergranular corrosion (IGC) and pitting corrosion. In this study, a low-carbon (0.02%) duplex stainless steel is subjected to various heat treatments at 450 to 950 °C for 30 min to 10 h. The heat-treated samples then undergo ASTM IGC and pitting corrosion tests, and the results are correlated with the microstructures obtained after each heat treatment. In the absence of Cr23C6 precipitation, σ-phase precipitates render this duplex stainless steel susceptible to IGC and pitting corrosion. Even submicroscopic σ-phase precipitates are deleterious for IGC resistance. Longer-duration heat treatments (at 750 to 850 °C) induce chromium diffusion to replenish the chromium-depleted regions around the σ-phase precipitates and improve IGC resistance; pitting resistance, however, is not fully restored. Various mechanisms of σ-phase formation are discussed to show that regions adjacent to σ-phase are depleted of chromium and molybdenum. The effect of chemical composition (pitting resistance equivalent) on the pitting resistance of various stainless steels is also noted.

  10. Influence of sigma-phase formation on the localized corrosion behavior of a duplex stainless steel

    International Nuclear Information System (INIS)

    Because of their austenitic-ferritic microstructures, duplex stainless steels offer a good combination of mechanical and corrosion resistance properties. However, heat treatments can lower the mechanical strength of these stainless steels as well as render them susceptible to intergranular corrosion (IGC) and pitting corrosion. In this study, a low-carbon (0.02%) duplex stainless steel is subjected to various heat treatments at 450 to 950 C for 30 min to 10 h. The heat-treated samples than undergo ASTM IGC and pitting corrosion tests, and the results are correlated with the microstructures obtained after each heat treatment. In the absence of Cr23C6 precipitation, σ-phase precipitates render this duplex stainless steel susceptible to IGC and pitting corrosion. Even submicroscopic σ-phase precipitates are deleterious for IGC resistance. Longer-duration heat treatments (at 750 to 850 C) induce chromium diffusion to replenish the chromium-depleted regions around the σ-phase precipitates and improve IGC resistance; pitting resistance, however, is not fully restored. Various mechanisms of σ-phase formation are discussed to show that regions adjacent to σ-phase are depleted of chromium and molybdenum. The effect of chemical composition (pitting resistance equivalent) on the pitting resistance of various stainless steels is also noted

  11. Microstructure and abrasive wear properties of M(Cr,Fe)7C3 carbides reinforced high-chromium carbon coating produced by gas tungsten arc welding (GTAW) process

    OpenAIRE

    Buytoz, Soner; M.Mustafa YILDIRIM

    2010-01-01

    In the present study, high-chromium ferrochromium carbon hypereutectic alloy powder was coated on AISI 4340 steel by the gas tungsten arc welding (GTAW) process. The coating layers were analyzed by optical microscopy, X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), X-ray energy-dispersive spectroscopy (EDS). Depending on the gas tungsten arc welding pa-rameters, either hypoeutectic or hypereutectic microstructures were produced. Wear tests of the coatings were c...

  12. Chromium oxidation state mapping in human cells

    Science.gov (United States)

    Ortega, R.; Fayard, B.; Salomé, M.; Devès, G.; Susini, J.

    2003-03-01

    The widespread use of chromium in industrial applications such as chemical production of pigments, refractory brick production, tanning, metallurgy, electroplating, and combustion of fuels has lead to human occupational exposure and to its increased introduction into the environment. Hexavalent chromium compounds are established carcinogens but their mechanism of cell transformation is not known. Up to now, no microanalytical technique was sensitive enough to allow the observation of chromium distribution, and oxidation state identification, within isolated cells at carcinogenic concentrations. In this experiment, we used successfully the ID-21 X-ray microscope to map Cr(VI) and total Cr distributions in cells exposed in vitro to soluble, and insoluble, Cr(VI) compounds. Exposure to soluble compounds, weak carcinogens, resulted in a homogeneous intracellular distribution of Cr, confirming by in situ measurement that Cr is present in the cell nucleus. Cr(VI) was never detected in cells which suggests a mechanism of rapid intracellular reducticn. On the other hand, exposure to insoluble compounds, strong carcinogens, also resulted in a homogeneous distribution of reduced forms of Cr in cells, and their nucleus. However, in this case, Cr(VI)-rich structures were observed into the cells suggesting that carcinogenicity is enhanced when oxidation reactions due to Cr(VI) chronic exposure are associated to Cr-DNA alterations.

  13. Dimensionally Controlled Lithiation of Chromium Oxide

    Energy Technology Data Exchange (ETDEWEB)

    Fister, Tim T. [Argonne National Lab. (ANL), Argonne, IL (United States); Hu, Xianyi [Northwestern Univ., Evanston, IL (United States); Esbenshade, Jennifer [Univ. of Illinois, Urbana-Champaign, IL (United States); Chen, Xiao [Northwestern Univ., Evanston, IL (United States); Wu, Jinsong [Northwestern Univ., Evanston, IL (United States); Dravid, Vinayak [Northwestern Univ., Evanston, IL (United States); Bedzyk, Michael [Northwestern Univ., Evanston, IL (United States); Long, Brandon [Argonne National Lab. (ANL), Argonne, IL (United States); Gewirth, Andrew A. [Univ. of Illinois, Urbana-Champaign, IL (United States); Shi, Bing [Argonne National Lab. (ANL), Argonne, IL (United States); Schlepütz, Christian M. [Argonne National Lab. (ANL), Argonne, IL (United States); Fenter, Paul [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-12

    Oxide conversion reactions are an alternative approach for high capacity lithium ion batteries but are known to suffer from structural irreversibility associated with the phase separation and reconstitution of reduced metal species and Li2O. In particular, the morphology of the reduced metal species is thought to play a critical role in the electrochemical properties of a conversion material. Here we use a model electrode with alternating layers of chromium and chromium oxide to better understand and control these phase changes in real-time and at molecular length scales. Despite lacking crystallinity at the atomic scale, this superstructure is observed (with X-ray reflectivity, XR) to lithiate and delithiate in a purely one-dimensional manner, preserving the layered structure. The XR data show that the metal layers act as nucleation sites for the reduction of chromium in the conversion reaction. Irreversibility during delithiation is due to the formation of a ternary phase, LiCrO2, which can be further delithiated at higher potentials. The results reveal that the combination of confining lithiation to nanoscale sheets of Li2O and the availability of reaction sites in the metal layers in the layered structure is a strategy for improving the reversibility and mass transport properties that can be used in a wide range of conversion materials.

  14. Chromium--a material for fusion technology

    International Nuclear Information System (INIS)

    Due to their low neutron-induced radioactivity chromium based materials are considered to be candidates for structure materials in fusion technology. In this paper investigations are presented of unirradiated chromium with a purity of 99.96% (DUCROPUR) and a dispersion strengthened chromium alloy Cr5Fe1Y2O3 (DUCROLLOY). Both materials have been produced in a powder metallurgical route. Mechanical tests of smooth and pre-cracked specimens have been performed in a wide temperature range. Below 280 deg. C the fracture toughness values of DUCROPUR are very low (1/2), above the transition temperature they exceed 500 MPa m1/2. Large plastic deformations have been observed. DUCROLLOY does not indicate such a significant increase of fracture toughness in the tested temperature range. But above 400 deg. C large plastic deformations can be obtained in bending samples, too. The fatigue crack propagation behaviour of DUCROPUR at 300 deg. C is similar to that of a ductile metal

  15. Improvement of wear resistance of sprayed layer on 52100 steel by friction stir processing

    Science.gov (United States)

    Rahbar-kelishami, A.; Abdollah-zadeh, A.; Hadavi, M. M.; Seraj, R. A.; Gerlich, A. P.

    2014-10-01

    The influence of friction stir processing (FSP) on wear resistance is studied on a thermally sprayed coating in terms of microstructure and mechanical properties. A high-chromium steel coating sprayed on AISI 52100 steel has been processed, and it is shown that FSP can improve the sprayed layer wear resistance compared to the as-sprayed and quenched and tempered condition. It is suggested that improved toughness is the main contribution to wear performance rather than hardness. It is observed that FSP provides increased hardness and toughness simultaneously, while tempering of the quenched AISI 52100 steel increases toughness while hardness decreases.

  16. Cleaning the magnesium oxide contaminated stainless steel system using a high temperature decontamination process

    International Nuclear Information System (INIS)

    A high pressure and high temperature (HTHP) system made of stainless steel-316, that simulates the reactor coolant systems of pressurized water reactors has been constructed for carrying out experimental investigations on power reactor water chemistry. After two months of operation at 280 C, magnesium was observed in the coolant. This was attributed to the failure of some heater pins that contained magnesium oxide as insulator. This magnesium oxide got distributed over the entire system. In order to remove the magnesium that had deposited and reacted over the oxide film formed over the stainless steel surfaces, the system was chemically cleaned using a mixture of nitrilo-tri-acetic-acid (NTA) and N2H4 at high temperature. The chromium containing oxide film formed over the stainless steel surfaces are normally removed using oxidizing pretreatment followed by treatment with reducing formulation. A minimum of three such cycles are required to complete the dissolution of contaminated oxide film. It has been proved elsewhere that chromium-containing oxides can be dissolved by simple chelating agents but at a relatively higher temperature (150-180 C) with NTA. Thus, NTA based process was tested for its capability to remove the magnesium contaminated oxide film formed over stainless steel. In addition to stainless steel, the system has few carbon steel areas. Hence, the compatibility of stainless steel and carbon steel to the NTA-N2H4 mixture was determined. Tests were carried out at different concentrations of NTA and at different pH. It was observed that carbon steel corrosion rates were quite high at low pH. With increasing pH, the corrosion rate decreased. The surface roughening observed at low pH was not observed at pH 8.0. Hence, it was decided to carry out the cleaning at pH 7.0 and with NTA concentration of 5 mM. Visual examination of the test flanges after the cleaning indicated complete removal of the oxide film. Results of chemical analysis indicated that

  17. Influence of ferrite decomposition mechanisms on the corrosion resistance of an aged duplex stainless steel

    International Nuclear Information System (INIS)

    The effect of long term aging of a duplex stainless steel type X6 CrNiMoCu25-6 on pitting and intergranular corrosion was investigated by various electrochemical methods including cyclic potentiodynamic tests, potentio-kinetic tests and DL-EPR (Double Loop Electrochemical Potentio-kinetic Reactivation) tests. It was established that the spinodal decomposition of ferrite (α' + G) after aging at 400 C during 1000 h leads to localized chromium depletion (wavelength 20 nm) without any detrimental effect on the pitting and intergranular resistance of this steel in synthetic sea water, compared to the annealed steel. However, aging at 500 C for 1000 h generates carbides and intermetallic phases by nucleation and growth producing larger chromium depleted areas, which results in lower pitting and intergranular corrosion resistance in synthetic sea water. (authors)

  18. A REVIEW OF BIOSORPTION OF CHROMIUM IONS BY MICROORGANISMS

    OpenAIRE

    Inga Zinicovscaia

    2012-01-01

    Due to its widespread industrial use, chromium has become a serious pollutant in diverse environmental settings. The main source of chromium pollution including the Republic o Moldova is industry. It is a great need to develop new eco-friendly methods of chromium removal. Biosorption of heavy metals is a most promising technology involved in the removal of toxic metals from industrial waste streams and natural waters. This article is an extended abstract of a communication presented at the...

  19. CHROMIUM INDUCED CYTOTOXICITY IN BLACKGRAM (VIGNA MUNGO L.)

    OpenAIRE

    A. Chidambaram ، P. Sundaramoorthy ، A. Murugan ، K. Sankar Ganesh ، L. Baskaran

    2009-01-01

    Chromium is known to be highly toxic to biological systems. This study was designed to determine the mutagenic effects of different concentrations (0, 10, 25, 50, 100 and 200 mg/L) of hexavalent chromium on root tip cells of blackgram (Vigna mungo L. Hepper). The blackgram seeds were equi-spacially arranged in sterilized petriplates lined with filter paper and they were treated with different concentrations of chromium solution. In germination studies, the morphological growth parameters such...

  20. Processes affecting the remediation of chromium-contaminated sites.

    OpenAIRE

    Palmer, C.D.; Wittbrodt, P R

    1991-01-01

    The remediation of chromium-contaminated sites requires knowledge of the processes that control the migration and transformation of chromium. Advection, dispersion, and diffusion are physical processes affecting the rate at which contaminants can migrate in the subsurface. Heterogeneity is an important factor that affects the contribution of each of these mechanisms to the migration of chromium-laden waters. Redox reactions, chemical speciation, adsorption/desorption phenomena, and precipitat...