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ONLINE ISSN: 1347-5460
PRINT ISSN: 0915-1559

ISIJ International Vol. 42 (2002), No. Suppl

  • Consideration and Practice of Science, Technology and Strategy for Minimizing CO2 Emission in Chinese Steel Industry

    pp. S1-S4

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    DOI:10.2355/isijinternational.42.Suppl_S1

    In order to minimize CO2 emission from iron and steel-making processes to abate greenhouse gas impact, the considerations and some practice of science and technology as well as its strategy completed and on going in Chinese steel industry are summarized. Two available ways for the minimizing in China so far:
    (1)Minimizing carbon-consumption (fossil energy-saving) in all the processes of steel industry which is the most realizable measure for reducing CO2 emission.
    (2)To look for new alternative reaction medium in the processes where producing more CO2 like H2 in blast furnace etc and new processes for iron and steel making which discharge less CO2 .
    Some new ideas like macro-based measures are put forward for minimizing CO2 emission in steel industry.
  • Development of Waste Plastics Recycling Process Using Coke Ovens

    pp. S10-S13

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    DOI:10.2355/isijinternational.42.Suppl_S10

    The Japan Iron & Steel Federation, as its voluntary energy-saving action plan, proposed a 10% energy reduction by 2010 with 1990 as the basis. Further, it has put forward an additional 1.5% energy saving by the use of waste plastics as a metallurgical raw material. The investigation of the use of waste plastics by the steel industry has mainly focused on processing in blast furnaces. On the other hand, the coking process is considered to be a promising area to which the thermal decomposition of waste plastics is applicable because the process involves coal carbonization at a high-temperature in reducing atmosphere.
    To evaluate the conversion rate of various waste plastics after carbonization using coke ovens, laboratory tests and actual coke oven tests were conducted. As a result, the yield of coke, gas, tar and light oil were 20%, 40% and 40%, respectively. And it was found that the 1% addition of waste plastics in raw coal did not deteriorate the coke strength. Waste plastics recycling process using coke ovens started at Nippon Steel Nagoya and Kimitsu works in 2000.
  • Characterising the Radio Frequency Plasma Source for Glow Discharge Optical Emission Spectroscopy

    pp. S101-S105

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    DOI:10.2355/isijinternational.42.Suppl_S101

    The radio frequency (RF) powered source is the most stable and capable analytical source available for glow discharge optical emission spectroscopy (GD-OES). It allows the direct analysis of both conductive and non-conductive samples on the same source, without changing the source. Recent developments in RF generators and components have further improved the performance of these sources, and now allow the routine measurement of additional RF parameters such as applied voltage and DC bias voltage. Theoretical studies of the fundamental characteristics of the RF source are providing deeper understanding of how they work, and combined with the new measurement tools will lead to further improvements in analytical performance. Recent theoretical and experimental work on the RF plasma source will be presented. These studies will be illustrated with some recent applications: in metals analysis, plus a hard coating and a non-conductive coating.
  • Some New Advances in Material Analysis Using Plasma Spectrometry

    pp. S106-S113

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    DOI:10.2355/isijinternational.42.Suppl_S106

    Some new advances in material analysis using plasma spectrometry with an emphasis on the analysis of solids, especially metals and alloys have been reviewed. The plasma spectrometries reviewed include inductively coupled plasma(ICP)-, microwave plasma torch(MPT)-, glow discharge(GD)- and laser induced plasma(LIP)-atomic emission spectrometry(AES)/mass spectrometry(MS). It is shown, for direct analysis of solid materials the GD-AES/MS and LIPS will play a major role though electrothermal vaporization(ETV)-, laser ablation-ICP/MPT may also occupy some places.
  • High Power Nitrogen Microwave Induced Plasma for the Determination of Some Trace Elements in Steels by Atomic Emission Spectrometry with Hydride Generation Technique

    pp. S114-S121

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    DOI:10.2355/isijinternational.42.Suppl_S114

    An annular-shaped high power nitrogen microwave induced plasma (N2-MIP) sustained at atmospheric pressure by an Okamoto cavity has been used as a new excitation source for atomic emission spectrometry (AES). In the preliminary study of high power N2-MIP-AES, the background equivalent concentrations and detection limits for a number of elements were measured at the most sensitive wavelengths of the elements by using a conventional solution nebulization as a sample introduction method. The detection limits obtained for the elements of interest are inferior by approximately one to two orders of magnitude compared with those obtained in this laboratory by a conventional argon inductively coupled plasma atomic emission spectrometry with solution nebulization. Subsequently, the combination of high power N2-MIP-AES with continuous-flow hydride generation technique was examined for the sensitive determination of such hydride-forming elements as antimony, arsenic, selenium and tellurium. Under the optimized experimental conditions, the best attainable detection limits at Sb(I)217.581, As(I)228.812, Se(I)196.026 and Te(I)214.281 nm by use of N2-MIP-AES coupled with hydride generation were 4.46 ngSb/ml, 2.99 ngAs/ml, 0.86 ngSe/ml and 15.0 ngTe/ml with linear dynamic ranges of three to four orders of magnitude in concentrations. After the interference study, the present method has been applied to the determination of trace concentrations of the above-mentioned hydride-forming elements in several steel standard reference materials issued by The Japan Iron and Steel Federation. The results obtained by the proposed method were in good agreement with the certified values.
  • Determination of Pb, Ag, Cu and Mn in Steel by Electrothermal-Atomic Absorption Spectrometry with Direct Atomization of a Solid Sample

    pp. S122-S127

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    DOI:10.2355/isijinternational.42.Suppl_S122

    When a small amount of metallic sample such as steel was heated in a graphite furnace used on electrothermal-atomic absorption spectrometry (ET-AAS), trace Pb, Ag, Cu and Mn in the sample were evaporated out of it, atomized and determined by AAS. A small sample was used for one determination. Mass of the sample was from about 20 to 600 μg. A graphite furnace was continuously used to atomize an analytical sample one by one. Appearance time and shape of an atomic absorption signal were affected by heating temperature of the graphite furnace (so-called atomization temperature). The appearance time of the signal shifted early with an increase in atomization temperature. Peak area of the signal was proportional to concentration of trace element in a sample, but height was not. Therefore, peak area of the signal was measured for determination of the trace elements. Detection limits of Pb, Ag, Cu and Mn in steel were 0.034 μg g-1 (for 500 μg of sample), 0.01 μg g-1 (600 μg), 0.3 μg g-1 (300 μg) and 0.8 μg g-1 (50 μg), respectively. By the way, an absorption signal of Pb consisted of two peaks that first one is small and another is large. The origin that two peaks were generated was examined by interruption of atomization for a solid sample and by heat-treatment of a solid sample before atomization. It became clear that the first peak was made from Pb in grain boundary of polycrystalline steel and another peak was made from Pb as particle in grain of the steel. Similarly trace Ag, Bi and Zn in polycrystalline steel showed double peak signals. As evaporation rate of trace Cu and Mn in a grain of steel was very slow, heating for atomization was repeated several times while absorption signal of Cu or Mn was detected .
  • Recent Developments in Laser-induced Breakdown Spectrometry

    pp. S129-S136

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    DOI:10.2355/isijinternational.42.Suppl_S129

    When a pulsed high-powered laser beam is focused on a target material, breakdown of the sample occurs and eventually results in the formation of a transient, and highly energetic plasma. Laser-induced breakdown spectrometry (LIBS) is a novel method of trace elemental analysis based on optical emission of laser-induced plasma. This article describes the theoretical and experimental results of the laser-induced plasma formation, recent advances in instrumentation and analytical techniques used for LIBS. The main focus is on recent developments such as portable instrumentation and novel applications such as analysis under water and in hostile environments. A brief review of some fundamental studies is also prepared and discussed.
  • Rapid Analysis of Steel by ICP-AES and ICP-MS with Laser Ablation Solid Sampling

    pp. S137-S139

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    DOI:10.2355/isijinternational.42.Suppl_S137

    Along with production control in steel making, the maintaining and improving quality has strongly required the development of a rapid and accurate method for the analysis of steel sample. A cw-Q-switched Nd-YAG laser was used in a laser ablation (LA) system for rapid analysis of steel using inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spectrometry (ICP-MS). The problems accompanying with the LA such as the quantity of fine particles produced by adjusting the laser radiation conditions. Also the contamination from impurity in the argon gas used to produced the ICP was reduced by zirconium purifier. A rapid method with high accuracy was established for steel analysis.
  • Fundamental Experiments on the H2 Gas Injection into the Lower Part of a Blast Furnace Shaft

    pp. S14-S18

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    DOI:10.2355/isijinternational.42.Suppl_S14

    It is necessary to reexamine basically an ironmaking process in order to reduce CO2 emission and energy consumption in a blast furnace. Especially, direct reduction from wustite (FeO) to iron (Fe) stage of iron ore sinter with solid carbon in the blast furnace is a strong endothermic reaction. H2 injection from the lower part of the shaft at temperatures from 1173 to 1373K can be considered more effective for the increase of the reduction degree from FeO to Fe. The effective conditions of H2 ratio in CO-CO2-H2-N2 mixture and the reduction temperatures have been investigated in the bed packed with sinter by comparing the reduction degrees from FeO to Fe between one method blown all the gases into the alumina ball bed (all gas mixed injection method or Method A) and the other method blown only H2 through another nozzles into the lower end of the sinter bed without mixing (H2 non-mixed injection method or Method N).
    In the gas composition (CO+H2)/(CO+CO2+H2)=0.75 at 1173 K determined by taking into account those in the blast furnace, the reduction rate was enhanced in the case of Method N. From comparison between the reduction degree after 90 min in the case of Method N and that in the case of Method A, the reduction degree of Method N is about 1.2 times higher than that of Method A under each condition of H2/(CO+H2)=0.1 or 0.3. Under the condition of (CO+H2)/(CO+CO2+H2)=0.75 at the reduction temperature of 1273 K, the reduction rate in the case of Method N is also higher than that in the case of Method A.
  • Spectroscopic Two-dimensional Observation of Flames in an Industrial Furnace for Steel Processing

    pp. S140-S144

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    DOI:10.2355/isijinternational.42.Suppl_S140

    In this study, a spectroscopic method is applied to measure two-dimensional (2D) distributions of flame temperatures during regenerative combustion of natural gas with highly preheated air in a test furnace of industrial size. By using a CCD camera fitted with an optical bandpass filter, the 2D distributions of the continuum emission from soot particles in premix and diffusion flames are measured at two different wavelengths. Subsequently, the temperature is determined on the basis of the two-color 2D thermometry, in which the ratio of the 2D emission intensity distributions is converted into the 2D temperature distribution with much higher spatial resolution in comparison with those obtainable by thermocouples. The emission profiles of NO radiation also were measured and the results are discussed in conjunction with difference in the temperature profiles of the flames.
  • Dezincing Behavior from Iron and Steelmaking Dusts by Microwave Heating

    pp. S19-S22

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    DOI:10.2355/isijinternational.42.Suppl_S19

    Recycling of valuable metals such as Zn, Pb is a key issue for environmental protection and efficient utilizations of valuable metals. In order to recover Zn and Pb from iron and steelmaking dusts, the recovery process of these dusts by microwave heating was investigated.
    Zn and Pb were almost 100% recovered from these dusts by microwave heating. In the first stage of this process, reduction of Fe2O3 proceeded prior to that of ZnO. In the second stage, when the temperature of the sample was above 900°C, ZnO was reduced and Zn was vaporized.
  • Numerical Simulation of the Moving Bed Furnace for Iron Scrap Melting

    pp. S23-S27

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    DOI:10.2355/isijinternational.42.Suppl_S23

    From the viewpoints of the limited deposit of natural resources and the protection of global environment, utilization of iron scrap is strongly requested. For estimating the effectiveness of the moving bed type scrap melting furnace, a two-dimensional mathematical model has been proposed, which considered transport phenomena of heat, mass and momentum together with melting and chemical reactions in the furnace for iron scrap melting. Numerical simulation was conducted to investigate in-furnace phenomena and effects of operating conditions on the process stability. According to the numerical results, the blast preheating was very effective for reducing coke consumption, because the coke rate can be reduced to 200 kg/t when it preheated to 673 K without oxygen enrichment. As the results, the process characteristics such as distributions of gas concentration, temperature and velocity have been obtained; they are useful to evaluate the performance of the iron scrap melting furnace and to improve the operations leading to less energy consumption and more iron scrap melting.
  • Influence of Sulfur Activity on the Reforming Reaction during Production of Iron Carbide with CO-CH4-H2-H2S Mixtures in Fluidized Bed

    pp. S28-S32

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    DOI:10.2355/isijinternational.42.Suppl_S28

    Iron carbide was produced in a laboratory scale fluidized bed by carburizing reduced iron with CO-CH4-H2-H2S mixtures at 873K. The rates of carbide formation and steam reforming of methane have been measured by means of X-ray diffraction for the sampled particles and the outlet gas analysis. On the influence of sulfur activity and pressurization in the carburizing atmosphere, special attention was paid.
    With an increase in the total pressure, the carburization rate increases. The carburization with CH4 proceeds to some extent, but that with CO-H2-H2O-H2S mixtures is the predominant reaction. At as low temperature as 873K, the rate of the reforming reaction is very slow and almost independent of the total pressure. Sulfur adsorbed on the surface of pores of reduced iron can suppress the decomposition of the iron carbides and the precipitation of free carbon, but it also retards the reforming reaction by poisoning the catalytic effect of reduced iron. Addition of some water vapor to the reaction gas also prevents the decomposition and the precipitation.
  • Energy and Pollutants Reducing Technologiesin New Ironmaking Processes at POSCO

    pp. S33-S37

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    DOI:10.2355/isijinternational.42.Suppl_S33

    The environmental assessment of new ironmaking processes at POSCO was carried out by focusing on the emissions reduction of air pollutants and CO2 in comparison to blast furnaces. Through the assessment, the environmental benefits of new ironmaking processes can be elucidated especially in respect of the reduction of SOx and NOx emission levels. In addition the new ironmaking processes demonstrate that CO2 emission reduction is enabled through the further energy optimization technological developments. In this respect, a technological approach to energy optimization in new ironmaking processes is introduced and discussed
  • Effect of Boron Addition on Structure and Properties of Low Carbon Bainitic Steels

    pp. S38-S46

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    DOI:10.2355/isijinternational.42.Suppl_S38

    The effect of trace boron in steels, especially the influence of boron on microstructure and properties of low carbon bainitic steels were summarized. It was pointed out that the hardenability of boron steels is determined by non-equilibrium boron segregation on grain boundaries. The synergistic effect of boron with other elements can enhance the boron effect. The abnormal boron segregation on the moving new grain boundaries is the basic reason of the boron retarding the recrystallization of deformed austenite, the addition of copper and niobium will increase this effect. The addition of boron accelerates the strain induced niobium carbonitride precipitation, and trace boron can refine the microstructure and improve the mechanical properties of HAZ. The mechanisms of boron effect were also expounded preliminarily in this paper.
  • Drawing Behavior of Pearlitic Steel Wire Rods Controlled by Boron Addition in Medium Carbon Steel

    pp. S47-S51

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    DOI:10.2355/isijinternational.42.Suppl_S47

    One of the most effective methods to increase the productivity and cost down in wire manufacturing is eliminating the patenting heat treatment during drawing process. For that purpose, the ductility increase of wire rods is essential to draw wire without breakage. Dilute pearlite, i.e., pearlitic structure with low cementite volume fraction, would be optimum microstructure for increasing the drawing strain, because ferrite-pearlite interface and cementite, which act as void initiation sites, are reduced. To obtain such microstructure in production line, addition of boron was examined. As results, mechanical properties of eutectoid steel are little affected by boron addition. But, in boron added medium carbon steel, ductility is enhanced, especially large elongation at sever deformed wire after bluing. It would be due to increase the strain hardening rate by reducing of proeutectoid ferrite and cementite stabilization.
    x

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  • Towards Sustainable Steelmaking – an LCA perspective

    pp. S5-S9

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    DOI:10.2355/isijinternational.42.Suppl_S5

    Life Cycle Analysis studies have been undertaken for a range of steelmaking routes, including conventional and emerging technologies. It has been shown that the new iron and steelmaking technologies based on coal can match greenhouse gas emissions (GGE) from gas based reduction processes when credits for slag use in cement, and for electricity from offgas, are taken into account.
    There is a range of improvement opportunities that offer the potential for major further reductions in GGE – a 50% reduction is a realistic target over time. From a GGE perspective, there are clearly benefits in integrating steel production with electricity generation and cement production; this is a good example of an industrial ecology opportunity.
    To support the move towards sustainability, BHP Billiton has used its LCA capability to develop two software tools to enable architects/building industry and school students to develop an understanding of energy and GGE in building systems and lifestyle issues, respectively.
    While GGE is now the major concern, it must also be recognised that other impacts of the steel production chain, eg those related to fresh water, will increasingly need to be taken into account.
  • Effect of Chromium and Boron Additions on the Warm Rolling Behavior Of Low Carbon Steels

    pp. S52-S56

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    DOI:10.2355/isijinternational.42.Suppl_S52

    The warm rolling of steels within the ferrite region can be a cost effective method of producing certain sheet materials. However, in the presence of solute carbon atoms, the rate sensitivity of the material can be affected as a result of dynamic strain ageing (DSA). This can significantly influence the microstructural development during processing, particularly due to the suppression of shear band formation. Shear bands help promote the development of a strong {111} texture during annealing, the presence of which is necessary to ensure highr-values in the final product. Therefore, the warm rolling of low carbon (LC) steels usually results in products with poor formabilities. However, it is known that the DSA behavior can be modified by the addition of elements such as boron and chromium. Three experimental low carbon steels with various additions of Cr and B were warm rolled; their behaviors are compared to that of a standard LC material. It was found that these additions promote the formation of shear bands at somewhat higher rolling temperatures than in the unalloyed steel, thus potentially resulting in stronger {111} recrystallization textures. Therefore, additions of Cr and B could lead to the production of warm rolled LC steels with improved formabilities.
    x

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    3. Improved Utilization of Added B in 9Cr Heat-Resistant Steels Containing W ISIJ International Vol.42(2002), No.Suppl
  • Effect of Boron on Copper Induced Surface Hot Shortness of 0.1% Carbon Steel

    pp. S57-S61

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    DOI:10.2355/isijinternational.42.Suppl_S57

    Copper in steel is enriched at the steel/scale interface by the selective oxidation of iron and causes liquid embrittlement at the steel surface during hot working. The development of method for the suppression of the hot shortness is desired for the promotion of recycling of steels. Effect of boron on the hot shortness was investigated from the viewpoints of oxidation rate, grain size, micro-structures of Cu-enriched phase and penetration of the liquid Cu-enriched phase. Addition of a low content of boron is effective on the suppression of the hot shortness. This suppression is attributed to the effect of boron to restrict the penetration of liquid Cu-enriched phase into austenite grain boundaries.
    x

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  • Investigation of Boron Distribution in Martensitic 9% Cr Creep Resistant Steel

    pp. S62-S66

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    DOI:10.2355/isijinternational.42.Suppl_S62

    Chemical compositions of ferrite matrix and various other phases in a Fe - 0.17 wt.% C - 9.3 wt. % Cr - 1.55 wt.% Mo - 0.27 wt.% V - 0.015 wt.% N - 0.01 wt.% B creep resistant steel in as-received and crept conditions were analyzed with atom probe field ion microscopy. The results show the presence of some residual boron within the ferrite matrix. Analyses showed that boron was uniformly distributed within M23C6, M6C, MX, and Laves phases. Phosphor segregated to the M23C6 - ferrite matrix interface. The results are analyzed with thermodynamic calculations.
    x

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    3. Development of Continuous Casting Technology for Special Steel Wire Rod and Bar Tetsu-to-Hagané Vol.74(1988), No.7
  • Improved Utilization of Added B in 9Cr Heat-Resistant Steels Containing W

    pp. S67-S71

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    DOI:10.2355/isijinternational.42.Suppl_S67

    For the construction of ultra super critical (USC) power plant, 9Cr-3W base ferritic heat-resistant steels with relatively high B and no N have been investigated. Authors have been revealed in the previous report that the addition of 139ppm B significantly improves creep strength of the steels, whereas most of added B forms unidentified borides, which are deemed almost ineffective to creep strength. The effect of improved heat treatment on creep strength and distribution of B in precipitates is investigated to effectively utilize and decrease added B. As a result of the analysis of the extracted residue and characterization of precipitates using field emission Auger electron spectroscopy (FE-AES), most of added B still forms borides in the 92ppm B added steel. These composites are almost dissolved and the B content in M23C6 carbides is significantly increased by normalizing at 1423K. It is also found by FE-AES analysis that B content in M23C6 carbides near prior-austenite grain boundaries is relatively higher than that inside grains. Creep strength at 923K for the 92ppm B added steel normalized at 1423K is not improved at short times, but it is remarkably improved to almost the same level as the 139ppm B added steel at long times. This excellent creep strength is achieved resulting in improving microstructural stability through the effective utilization of added B by high-temperature normalizing.
    x

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    3. Development of Continuous Casting Technology for Special Steel Wire Rod and Bar Tetsu-to-Hagané Vol.74(1988), No.7
  • Effects of Boron Addition on Tempering Processes in an Fe-9Cr-0.1C Alloy Martensite

    pp. S72-S76

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    DOI:10.2355/isijinternational.42.Suppl_S72

    The effects of boron addition on the tempering processes of 0.1C-9Cr martensite have been studied. The alloys with and without 98ppm boron were prepared. The specimens austenitized at 1200ºC for 1.2ks were quenched into iced brine. The structure was consisted of α' martensite laths. They were heated at 10ºC/min to 900ºC. Temperature derivative of electric resistivity, dρ/dT, exhibited small increase at temperature around 740°C (reaction A), gradual decrease at temperatures between 750°C and 800°C (reaction B), large decrease at around 815°C (reaction C) and small increase at around 830°C (reaction D). Transmission electron microscopic observations showed that the reactions in the alloy with boron were related to the dissolution of cementite, the precipitation of M23(B·C)6 and M7(B·C)3, the austenite formation, and the dissolving of the carbides with further increase of austenite, respectively. In the alloy without boron, they corresponded to the dissolution of cementite, the precipitation of M7C3, the austenite formation, and the dissolving of M7C3 with further increase of austenite, respectively. The boron addition to Fe-lowC-highCr alloy promotes M23(B·C)6 formation and retards the α→γ transformation.
    x

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  • Effects of Boron and Nitrogen on Graphitization and Hardenability in 0.53%C Steels

    pp. S77-S81

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    DOI:10.2355/isijinternational.42.Suppl_S77

    The effects of B and N on the graphitization and the hardenability in 0.53 mass% C steels were investigated in order to utilize both effects of BN and free B on the properties of machine structural steels.
    The number of BN particles after normalizing heat treatment is increased by the increase in the amount of B or the decrease in N. In the steel that has lower content of N, BN can be resolved and finely precipitates during normalizing. BN provides the preferred site for graphite nucleation, so the distribution of graphite particles is very similar to that of BN prior to graphitization. The growth rate of graphite particle is controlled by diffusion of carbon in ferrite matrix, and the time required for completion of the graphitization is the function of the radius of graphite particles after the end of graphitization, which depended upon the number of graphite particles. The hardenability of the steels can be estimated by the amount of sol. B at heating temperature prior to quenching. Sol. B of 6 ppm or more is required to obtain full martensitic microstructure.
    The preferable graphite distribution and the enough hardenability of the steels can be simultaneously achieved by optimizing the heating process and the amount of boron and nitrogen
    x

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    3. The Nature and Consequences of Coherent Transformations in Steel ISIJ International Vol.43(2003), No.3
  • Glow Discharge Optical Emission Spectrometry – Activities and Opportunities in the Field of Depth Profile Analysis

    pp. S82-S85

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    DOI:10.2355/isijinternational.42.Suppl_S82

    Glow discharge optical emission spectroscopy (GD-OES) as a depth profiling technique is briefly reviewed. The quantification technique based on emission yields, defined as the analytical signal per unit weight of the analyte, is described. Current standardisation work on applications to zinc and aluminium based metallic coatings is reviewed. Recent work on non-conductive applications using radio frequency (RF) sources is presented. It is shown that practical possibilities to determine discharge parameters exist, but is more complex to use than for the DC source. Furthermore, the strong influence of hydrogen on emission yields is demonstrated. A "matrix correction" technique to deal with this problem is discussed. It is also shown that in spite of all the corrective measures, there still exist artefacts not completely understood, making it necessary to do "matrix-matched" calibrations for certain applications. For thin film applications, it is demonstrated that state-of-the-art GD-OES systems are capable of a depth resolution similar to e.g. SIMS and AES. For quantification of very thin layers, the hydrogen correction must be considered. In addition, it is shown that short-lived molecular emission can influence the analytical results. A method to deal with this effect is presented and discussed.
  • Improvement of the Information Depth in In-depth Analysis by Radio-frequency-powered Glow Discharge Optical Emission Spectrometry

    pp. S87-S92

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    DOI:10.2355/isijinternational.42.Suppl_S87

    Two novel measuring methods in radio-frequency-powered glow discharge optical emission spectrometry: an amplitude modulation technique and a bias-current conduction technique, are reviewed. They are both effective for the in-depth analysis of relatively thin films. In the amplitude modulation technique, radio-frequency voltages supplied to the glow discharge lamp are modulated at a very low frequency, which leads to a reduction in the sputtering rate as well as a cyclic variation in the emission signal. With a lock-in amplifier, the emission intensities can be selectively detected with a better signal-to-noise ratio, although the sampling amount is reduced and thus the emission intensities decrease. In the bias-current conduction technique, a d.c. bias current is conducted by connecting an electric circuit consisting of a low-pass filter and a load resistor to the glow discharge lamp. The bias current can introduce a large number of electrons into the plasma, thus leading to an enhancement in the emission intensities from the plasma, whereas the sputtering rate is reduced due to the deceased d.c. bias voltage. Both of the techniques can contribute to an improvement in the information depth in glow discharge optical emission spectrometry
  • Present Status of Microstructural Characterization of Steel by Analytical Methods

    pp. S93-S100

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    DOI:10.2355/isijinternational.42.Suppl_S93

    A review on recent microstructural characterization of iron and steel by analytical methods is described. The bulk chemical composition of iron and steel is determined by chemical analytical methods in production lines so as to obtain their target properties or microstructures. These analytical methods enable a reliable and reproducible composition to be rapidly determined. On the other hand, microscopic analyses for a thin layer or small area are also important, since steel products demonstrate a heterogeneous microscopic chemical composition, which affects their properties. For instance, glow discharge optical emission spectrometry (GD-OES), which is a plasma spectrometric and microscopic method, rapidly provides quantitative depth profiles of thin layers such as coatings formed on the surface of iron and steel. In this paper, several examples analyzed by GD-OES are demonstrated together with the advantages of such analyses. Besides GD-OES, other microscopic analytical methods are applied for elucidating the mechanism of microscopic phenomena in steel products. Electron spectroscopy, mass spectrometry, electron microscopy and other methods are microscopic analytical methods, but it takes a long time to prepare and measure samples using these methods. In addition, in spite of the usefulness of these microscopic analytical methods, it may be difficult to quantitatively compare results analyzed by these methods with each other. This is because steel products are generally composed of various microstructures, and therefore the results differ from one analyzed area to another one. The present paper reviews the present status of not only the usefulness of a microscopic analysis such as GD-OES but also the meaning of the microscopically analyzed results.
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