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ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 73 (1987), No. 3

  • Electromagnetic Casting Up to Date and Future

    pp. 403-410

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    1. Meniscus Shape of Molten Steel under Alternating Magnetic Field ISIJ International Vol.32(1992), No.4
    2. Basic Study of Horizontal Electromagnetic Levitation Casting of Aluminum Sheet ISIJ International Vol.36(1996), No.Suppl
    3. 日本鉄鋼協会第113回講演大会 講演概要集(II) その1 Tetsu-to-Hagané Vol.73(1987), No.5
  • Metalluraical Aspects of Recent Developments in Titanium Alloys

    pp. 411-419

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  • Phase Transformation and Heat Treatment in Titanum Alloys

    pp. 420-426

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  • Internal Corrosion of Food Cans

    pp. 427-436

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    Readers Who Read This Article Also Read

    1. Present Status of Electroslag Remelting Process Tetsu-to-Hagané Vol.73(1987), No.2
    2. ASEANで成功する方法(?) Tetsu-to-Hagané Vol.74(1988), No.12
    3. Development of Continuous Casting Technology for Special Steel Wire Rod and Bar Tetsu-to-Hagané Vol.74(1988), No.7
  • Activity Report of Surface Analysis Subcommittee of the Iron and Steel Analysis Committee, the Joint Research Society of ISIJ

    pp. 437-452

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  • High Temperature Measurement of the Effective Diffusivity of Gas through Coke and Graphite by the WICKE-KALLENBACH Method

    pp. 453-460

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    The WICKE-KALLENBACH method had not been applied to the high temperature measurement due to the difficulty of preventing gas leakage from the portion between the diffusion cell and a sample. However, this problem was overcome by devising the Na2O-SiO2 cement containing liquid phase at elevated temperatures.
    This technique made it possible to evaluate the effective diffusivity of Ar-He system through coke and graphite in a wide temperature range from 20 to 1300°C. The effective diffusivity for CO-CO2 up to 300°C and permeant fluxes for Ar and He up to 1000°C were also measured.
    From these measurements, molecular, KNUDSEN and surface diffusion through pores could be evaluated distinctively, the results of which showed the temperature dependence of molecular diffusivity as T1·66T1·69in coincidence with the theoretical value by CHAPMAN-ENSKOG.
    The technique proposed in the present work was also applied to the in situ measurement of effective diffusivity of Ar-He through coke in the course of oxidation with CO2 at 900°C.
    The variation of diffusivity with the increase in degree of reaction was found to be several times larger than that expected by the "Parallel pore" model.
  • Development of Integrated Process Computer System in Ironmaking Department

    pp. 461-468

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    A hierarchical computer system was developed for the control of Nos. 3 and 4 sinter plants at Chiba. This system consists of three layers; digital control system, process computer, and central computer at Chiba Works.
    Besides for the control of the sinter plants, the process computer system is scheduled to be extended in steps for the control of the other plants in the ironmaking department, to be eventually the integrated process computer system for the ironmaking process by using an exclusive computer. It enables the improvement of the maintenance efficiency.
    For the high future extensibility of the system, the process computer system adopted a general-purpose computer (IBM-4361) and software package ACS (Advanced Control System) for process control. Since, however, the ACS is a software for a continuous process such as petroleum refining process, various kinds of functional expansion was made for the ironmaking process.
    The 3-layer hierarchical system of Nos. 3 and 4 sinter plants at Chiba Works was completed in July 1985, and has brought about saving of the cost and increase of the efficiency in the operation.
  • Viscosities of Borate-base Binary Molten Oxides and Characteristic Features of the Viscosity of Molten Salts

    pp. 469-475

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    A clear understanding of characteristic features of molten salts requires quantitative discussions on their network structures. From this point of view, viscosities of pure molten borate and borate-base binary oxides, in which network structures would be formed, have been measured by using an oscillating-plate viscometer. Furthermore, characteristic features of viscosity of molten salts have been discussed on the basis of model theories. The results obtained are as follows:
    (1) Viscosities of molten B2O3 are expressed in the following non-Arrhenius equation:
    μ=0.103 exp (5.17×107/RT2) (in Pa·s)
    (2) As compared with the viscosities of molten B2O3, the viscosities of molten B2O3-2mol% SiO2 are high, while the viscosities of molten B2O3-2mol% ZnO, BaO, PbO, Na2O are low in that order. This order corresponds approximately to that of the relative strength of acidity→basicity for the oxides.
    (3) Since network forming melts have higher viscosity values, positive deviations from the viscosities calculated by using an equation for simple melts would provide a quantitative approach to the network structures of melts.
  • Calculation of Activities of the Constituents in FetO-(CaO+MgO)-(SiO2+P2O5) Slags by Regular Solution Model

    pp. 476-483

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    The chemical equilibria of gas-slag-metal reactions have been discussed to clarify the applicability of LUMSDEN'S regular solution model to oxygen distribution in steelmaking process. The slage studied are FetO-CaO, FetO-CaO-SiO2, FetO-MgO-SiO2, FetO-(CaO+MgO)-SiO2 and FetO-(CaO+MgO)-P2O5 systems. The influence of slag composition on the activity of iron oxide and the Fe3+/Fe2+ ratio has been discussed.
    It has been confirmed that the regular solution model is satisfied over wide composition range in above-mentioned steelmaking slags except for SiO2 saturation and FeO rich region. In has been possible by the use of the model to calculate activities of the constituents in FetO-(CaO+MgO)-(SiO2+P2O5), iso-activity lines for each component in FetO-CaO-SiO2 slags and contours of αFetO in FetO-MgO-SiO2 slags.
  • Wetting Behavior of Molten FeO-SiO2 Slag to Al2O3-SiO2 Refractories

    pp. 484-490

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    For the quantitative analysis on the infiltration of molten slag into pores in refractories, the wettability of an FeO-SiO2 slag was studied for Al2O3-SiO2 bricks and dense refractory plates by the sessile drop method in consideration of surface roughness on the samples. The results have been phenomenologically discussed together with those previously obtained in refractory capillarles. The conclusions are;
    (1) The contact angle is dependent on the ratio of the slag drop height to the width. As this ratio became smaller, the contact angle observed approached the value calculated on the presumption of the slag drop shape being a part of a sphere.
    (2) The time-dependency of the contact angles is intermediate on the refractory bricks between the typlcal ones on both the dense alumina and mullite refractories. The behavlor is correlative to the quantitative fractions of the minerals which the bricks are composed of.
  • Infiltration of Molten FeO-SiO2 Slag into Pores in Al2O3 Bricks with the Slagging Reaction

    pp. 491-497

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    This study reveals the quantitative analysis on the infiltration of molten slag into pores in bricks with the slagging reactions. The experiment was carried out with an FeO-SiO2 slag on practically used Al2O3-SiO2 bricks at 1 523 and 1 573 K, then semi-theoretical formulations were introduced for the interpretation in a connected pores system. A satisfactory explanation was presented to the experimental observations on the slagging infiltration of the molten slag in the industrial bricks through the characterization of the pores system and the correlative evaluations of immersion force, slagging reactivity and wetting behavior. The unified interpretaion then suggests the possibility for the anticipative estimation of the phenomenon out of the material natures concerned.
  • Effect of Mild Cooling in Mould upon Solidified Shell Formation of Continuously Cast Slab

    pp. 498-504

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    The effect of reducing heat flux density in continuous casting mould on the solidified shell formation has been studied in order to improve the irregularity of solidified shell thickness and to reduce longitudinal surface cracks. From theoretical considerations, mild cooling in the mould can be attained by making many grooves on the mould inner surface, since the heat transfer coefficient between the strand shell and the mould is lowered due to the air gap existence in the groove. Therefore the width of each groove should be minimized to prevent the molten powder from flowing into the groove.
    Experiments using the mould with small longitudinal grooves have been carried out in the curved continuous casting machine. From results of temperature measurements in the copper mould, the local heat flux density at 15mm below the mould meniscus is lowered to about two thirds of that of the conventional smooth surface mould. Both the irregularity of shell thickness and the surface quality of slabs are considerably improved.
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  • Mechanism of Formation of Surface Defects in Continuously Cast Stainless Steel Slabs Containing Titanium

    pp. 505-512

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    An investigation was carried out on surface defects in continuously cast stainless steel slabs containing titanium. Factors affecting the formation of two main surface defects, i.e. crust defects and cluster defects were examined. Furthermore, a study was made on the mechanism of formation of crusts at the meniscus in the mould.
    1) Two causes are pointed out for the fact that crusts are apt to form in these steels; a) titanium nitride inclusions in the molten steel act as effective substrates for the nucleation of solidified steel, and b) they react with iron oxide in a mould powder to form nitrogen gas blow holes which lower apparent thermal diffusivity of the molten steel.
    2) Cluster defects were formed by two different mechanisms; large size of cluster defects were originated from a piece of build-up in the tundish nozzle, and those of small size are caused by accumulation of the in-clusions at a certain position of the meniscus.
  • Production of High Carbon Chromium Bearing Steel in BOF-CC Process

    pp. 513-519

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    High carbon chromium bearing steel has been mainly produced by electric arc furnace-small ingot casting process. However application of continuously cast steel has been gradually expanded. In order to improve the rolling contact fatigue life of bearing steel, it is essential to decrease oxygen, titanium and sulfur contents in the steel and improve center line segregation.
    Taking these points into consideration, high carbon chromium bearing steel is produced through BOF-CC process. The contents of oxygen, titanium, phosphorus and sulfur are easily decreased by combining the hot metal pretreatment furnace-BOF-ladle refining process.
    The center line segregation is improved by the combined electromagnetic stirring technique. As a result, cleanliness of the steel and rolling contact fatigue life are improved. Based on good result of ball fatigue test, it can be expected to apply continuously cast steel to bearing ball use.
  • Package Melting Method of Titanium Alloy Scraps

    pp. 520-527

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    Concerning the product cost, the use of recycled scraps for the production of ingots of titanium alloys is of great importance. Thus, the authors have developed a new melting technique, called the package melting method, for titanium alloy scraps. The process is summarized as follows. At first, massive scraps, chips and turnings are packed together into the gutter regardless the size and type of scraps. Secondary, the gutter is set horizontally into vacuum furnace, melted with plasma electron beam or electron beam and cast into ingot continuously.
    Experiments carried out on Ti-6Al-4V alloy scraps result in the following conclusions.
    (1) Ingots obtained by this method have good surface quality and no shrinkage porosity and segregation.
    (2) Since the ingot has good workability with only a single melt, secondary melting is not necessary.
    (3) The bars produced from recycled scrap have mechanical properties equivalent to those of the bars from sponge.
    (4) Owing to the simple processing steps and high scrap ratio, this method has cost advantages over other melting method.
  • Surface Roughness Decrease of Rolls in Cold Rolling of Steel Strip

    pp. 528-535

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    The decrease in surface roughness of rolls in cold rolling of low carbon steel strip was investigated by using drawing-type rolling mill. From the result, the decrease in surface roughness could be reproduced as in practical cold rolling mill. The tests were performed to find the effects of the lubricants, and the materials of strip and rolls on surface roughness of rolls. The obtained results are as follows;
    For the same lubrication condition, the decrease in surface roughness of rolls is more rapid in rolling Al-killed steel strip than in rolling rimmed steel strip. That would be due to the higher yield stress of Al-killed steel than that of rimmed steel. The roughness decrease is smaller in the case of paraffinic oil than in the case of octyl-stearate oil for both All-killed steel and rimmed steel. The decrease in surface roughness of rolls is smaller for rolls containing higher chromium. It has been confirmed by ISOT that the reactivity of iron oxide and iron hydroxide with stearic acid is higher than that with oleic acid. And from drawing rolling experiment, lubricant containing stearic acid shows the higher lubricity and causes larger decrease in surface roughness of rolls than that containing oleic acid. Also lubricant containing iron soap gives larger decrease in suface roughness of rolls.
    Therefore, the corrosion wear mechanism plays an important role in the decrease in surface roughness of rolls in rolling of steel strip.
  • Effect of Temperature on Low-cycle Fatigue Properties of Ni-base Superalloys for HTGR

    pp. 536-543

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    In order to obtain fundamental information on the effect of test temperature on the low-cycle fatigue properties of two Ni-base wrought alloys, namely Inconel 617 and Hastelloy XR, a set of strain controlled fatigue tests has been carried out at temperatures up to 1000°C in air and partly in vacuum under a fully reversible triangular and a strain-hold waveforms.
    Cyclic hardening behaviors were observed at temperatures up to 800°C. The fatigue life was reduced with increasing temperature. At high temperatures above 800°C the following results were obtained. The difference of lives between in air and vacuum became larger. The intergranular failure was dominant and the range of transition temperature from transgranular to intergranular was 600800°C depending on the strain range and waveform.Experimental fatigue lives for both alloys were shorter than fatigue lives predicted by the universal slope method and 10% rule.
    Thus, the effects of creep deformation and high temperature oxidation on the fatigue properties were significant at high temperatures.
  • Toughness Evaluation of 1/2 Mo Steel Using for Pressure Vessel

    pp. 544-550

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    Experience of Accidents at petroleum-refining plants strongly demand improvements in the safety of facility operations. Brittle fracture at relatively low temperature is the most catastorophic type of accident of pressure vessel that can occur in use. To prevent it, various approaches of reliability evaluation have been taken. The most important factor in reliability evaluation is the toughness of the construction material. There are more than a few cases in which a fracture originated in lower toughness than expected.
    Pressure vessels of 1/2 Mo steel are the most widely used in such petroleum-refining facilities as naphtha, kerosene, and light oil hydrotreating reactors. The significance of their toughness has become highlighted resently.
    22 samples of 1/2 Mo steels, which had been in long-term service for pressure vessels, were investigated for the purpose of prediction of the vTrs of 1/2 Mo steel. It was found that the vTrs of 1/2 Mo steel can be estimated nondestructively by using the following parameter.
    vTrs(°C)= 22.6 X-32.59
    X= 100 (P+B)/ HV·N
    where P+B: Pearlite plus bainite fractions in the microstructure, HV: Vickers hardness, N: ASTM ferrite grain size No.
  • Effect of Applied Stress on Hydrogen Attack of 2 1/4 Cr-1Mo Steel

    pp. 551-557

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    Creep rupture tests in high pressure hydrogen and argon of 200 kgf/cm2 at 525 and 550°C were performed on two 2 1/4 Cr-1Mo steels indicated as P and Sn steels which have low and high density of voids by hydrogen attack, respectively. The results are as follows:
    1) Marked decrease in reduction of area was observed in hydrogen atmosphere after a certain rupture time in a stress-rupture time diagram. However, the decrease on Sn steel was observed at earlier rupture time than on P steel.
    2) Contrast to intragranular ductile fractrure in argon atmosphere, whole fracture surface of Sn steel consisted of grain boundaries with coalescent voids in hydrogen atmosphere. In the case of P steel, since only a few voids were grown on grain boundaries, micro cracks occurring around triple point of grain boundaries could not propagate along grain boundaries but combined with intragranular ductile fracture. This indicates that the number of voids are not increased under applied stress and the ductility loss in hydrogen atmosphere is determined by hydrogen attack resistance of steels.
    3) Applied stress accelerated void growth rate by 3-4 times. This can be understood by taking methane pressure to be 1 000-2 000 kgf/cm 2 and applying this value to a theoretical equation. The carbon activity corresponding to the methane pressure is 0.04-0.10.
  • Effect of Soft Interlayer on Charpy Impact Value of Flash Welded Zone

    pp. 558-564

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    The welded zone of a chain link manufactured by flash welding is generally softened due to the reduction of the amount of alloying elements during welding. The simulation test using the specimens which have soft interlayer materials was done to clarify the effect of softening on the mechanical properties of the welded zone. The results are as follows:
    1) Though the simulated specimen fractures at the soft layer on tensile tests, the tensile strength is higher than that of the soft materials. With decreasing the thickness of the soft layer the tensile strength in creases, but the elongation and the reduction of area considerably reduce.
    2) The impact value of the simulated specimens reduces with decreasing the thickness and the hardness of the soft material.
    3) The reasons for them are that the plastic deformation of the simulated specimens occurs within the soft layer and the specimens fracture before general yielding.
    4) The toughness of the welded zone in a chain link is improved by either making the softened layer of the welded zone thicker or reducing the degree of softening.
  • Quantitative Analysis of Electroplated Films and Chromate Film by Glow Discharge Spectrometry

    pp. 565-572

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    Factors which determine the Grim glow discharge characteristics, sputtering rateand emission yield were studied in order to obtain quantitative depth profiles of surface films on steel sheets using the glow discharge spectrometry (GDS).
    1) The sputtering rate of a specimen (with a constant composition) depends on the product of the effective discharge voltage and the courrent, being indifferent of the Ar pressure and the discharge modes (constant voltage, constant current and constant power).
    2) The emission yield (within the abnormal glow discharge reange) on the three modes increases depending on the Ar pressure.
    3) Some matrix effects are observed in the emission yield of zinc and iron for Zn-Fe alloy plating. The emission yield, therefore, should be corrected according to approximate alloy composition in order to obtain accurate results.
    4) GDS can also be applied for the analysis of very thin layers, such as chromate film on the top of tin plates. The coefficient of variance of the analysis of Ni, Su and Cr (chromate) layers (the total thickness 100 nm) is less than 5%.
  • 科学の即時性/小さな文化摩擦

    pp. 575-575,584

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