鉄と鋼
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
64 巻, 9 号
選択された号の論文の19件中1~19を表示しています
  • 上杉 年一, 井上 誠
    1978 年 64 巻 9 号 p. 1311-1312,1468
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
  • 雀部 実, 木下 豊
    1978 年 64 巻 9 号 p. 1313-1322
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    An experimental procedure to determine the permeability of dissolved oxygen gas in liquid slag has been developed using an oxygen concentration cell. A small amount of oxygen gas which permeated the liquid oxide from a pure oxygen compartment to a pure argon compartment was determined by the galvanic cell. The permeabilities of oxygen through CaO-SiO2-Al2O3 melts were found to be in the range of 3×10-19 to 6×10-18 moles / cm. sec. In separate experiments, the oxygen pressure change at the bottom of a column of slag was detected by another galvanic cell. By this method, it is not necessary to quench the specimen to determine the concentration profile of dissolved oxygen to obtain its diffusivity. The diffusion coefficients of oxygen in CaO-SiO2-Al2O3 melts were found to be in the range of 7×10-5 to 3×10-4 cm2/sec. The observed permeabilities and diffusion coefficients increased with increasing temperature at a fixed slag composition and with increasing content of network-modifier oxide at a constant temperature. The solubilities of oxygen gas in CaO-SiO2-Al2O3 melts were estimated from the permiabilities and diffusivities to be 2×10-15 to 2×10-14 moles/cm3.
  • 中西 恭二, 江島 彬夫, 鈴木 宰, 数土 文夫
    1978 年 64 巻 9 号 p. 1323-1332
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    Cold and hot model experiments have been made to investigate the kinetics of desulfurization of hot metal by magnesium granules injected with carrier gas. The followings are the major remarks obtained:
    (1) The desulfurization rate is remarkably enhanced when the bath surface is covered with inert gas.
    (2) It is theoretically predicted that a magnesium particle of 2 mm in diam. detatches from the gas jet of 200 m/sec in linear velocity and penetrates into molten iron.
    (3) By assuming the mass transfer of S as a rate controlling step, a theoretical prediction is made for the rates of desulfurization. The immersion depth of a lance significantly influences the rate of desulfurization ; it is preferable to release magnesium bubbles from the bottom of the bath.
    (4) The validity of the present model is shown by the plant scale experiments of 60 t in heat size.
  • 福沢 章, 中川 龍一, 吉松 史朗, 上田 卓弥
    1978 年 64 巻 9 号 p. 1333-1342
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    A mathematical model (resistance model) has been developed by assuming that reaction rates of the oxygen steelmaking process are limited by the mass transfer which is affected by the bath mixing caused by the jetted oxygen and the generated CO gas. The characteristics of this model are discussed through the comparison between the NRIM continuous steelmaking process and BOF process for the probale range of values of resistance coefficients and oxygen deliverly ratio, both being the essential factors in the model. As a consequence, it becomes clear that the resistance coefficient is independant on the furnace size and takes a value of practically constant range for each reaction.
    Simulated results of single (1 lance) and 2 (2 lances) staged co- and counter-current continuous steelmaking processes, BOF and VOD can be regarded to represent the characteristics of each process.
    From the foregoings, the assumption that the gas flow rates have an important role for the bath mixing can provide a valuable aid to understand the steelmaking reaction kinetics.
  • 高石 昭吾, 小舞 忠信, 村田 裕信, 平本 克房, 関原 博通
    1978 年 64 巻 9 号 p. 1343-1352
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    Behavior of hydrogen in steel in the steel-making and strand casting processes was studied.
    The results are summarized as follows:
    (1) The optimum procedure of sampling and analysis of hydrogen in liquid steel is determined.
    (2) Diffusible and non-diffusible hydrogen in cast slabs can be analyzed separately by the methods of glycerine extraction and vacuum heating extraction respectively.
    (3) Hydrogen content in liquid steel is about 2-4 ppm before tapping and increases abruptly during tapping. The amount of hydrogen increase is closely related to the humidity of atmosphere.
    (4) Segregation of hydrogen is observed at the center of slabs, the amount of which is affected by the nondiffusible hydrogen content in cavitiees.
    (5) Non-diffusible hydrogen content is confirmed to be proportional to the total volume of cavities which are formed during solidification.
    (6) The degree of hydrogen segregation at the center of slabs decrease with an increase of the thickness of equiaxed structure zone in slabs, because cavities in the zone are scattered uniformly and finely.
  • 田中 智夫, 田畑 綽久
    1978 年 64 巻 9 号 p. 1353-1362
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    For the purpose of measuring austenite-to-ferrite transformation temperatures in niobium-bearing steels during controlled rolling, various methods were investigated. The change in texture intensity as well as those in microstructure and strengths produced by deformation in the austenite-ferrite region was found to be useful for this purpose, those giving the same Ar3 temperature.
    Ar3 temperature rises with the increase in the amount of deformation in non-recrystallization region. The increment is, however, much larger for a coarse austenite grain structure than for a fine one. Regardless of the difference in initial austenite grain sizes, Ar3 temperature reaches the same value when the deformation in non-recrystallization region is increased to -70%. The rise in Ar3 temperature is due to strain-induced transformation and grain fragmentation caused by deformation bands.
  • 近崎 充夫, 添野 浩
    1978 年 64 巻 9 号 p. 1363-1370
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    Intergranular corrosion (IGC) susceptibility to Strauss test of metastable and stable austenitic stainless steels annealed at 500-800°C after solution treatment and cold drawing was investigated.
    The annealing temperature for giving peak IGC susceptibility ranged from 650 to 700°C in solution treated specimens and it dropped to lower temperatures, 550-600°C, in slightly and moderately cold drawn ones. With increasing the reduction of cold drawing, the IGC susceptibility became very small for all annealing temperatures tested. The critical reduction of cold drawing beyond which the IGC susceptibility diminished increased with increasing carbon content in steel.
    The effects of cold working and annealing on the IGC susceptibility of metastable austenitic stainless steels were very similar to those of stable ones. This suggests that the martensite phase induced by cold working of meastable austenitic stainless steels does not necessarily give an essential effect on the susceptibility to IGC.
    On the basis of electron microscopic observation of grain boundary morphologies and precipitated carbides in various specimens, the mechanism of the effect of cold working on the change in IGC susceptibility of these steels was discussed.
  • 沢田 進, 大橋 建夫
    1978 年 64 巻 9 号 p. 1371-1378
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    The effect of strength levels obtained by changing tempering conditions of quenched martensitic 3% Ni-Cr-Mo-V steel on susceptibility to temper embrittlement was examined by applying isothermal embrittling treatment. In addition, the fractured surfaces of Charpy impact specimens tested at different temperatures were also investigated in detail by using a scanning electron microscope.
    The main results obtained are as follows:
    (1) The temper embrittling rate and amount designated by the shift of FATT during embrittlement treatment of martensitic steels tempered for 6 hours clearly depend on tempering temperatures of 600°C, 630°C and 660°C after quenching. The steel tempered at a higher temperature tends to be embrittled more rapidly to a larger extent. The apparent activation energies for embrittlement depend on the tempering temperature; this implies that the microstructure affects segregation of embrittling elements to grain boundaries.
    (2) Intercrystalline fracture dominates brittle fracture in the vicinity of transition temperature region, although it decreases rapidly with decrease in the testing temperature. With the temperature decreasing, the intercrystallinely fractured region in a Charpy specimen appears only near the bottom of notch, which may indicate that the fracture mode changes with crack velocity as well as with difference between cleavage and grain boundary fracture strength.
  • 冨田 恵之, 宮本 啓太, 岡林 邦夫
    1978 年 64 巻 9 号 p. 1379-1388
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    A study has been made of the true fracture ductility in static tension at room temperature of a 0.42% C-Ni-Cr-Mo steel having mixed structure of martensite and bainite.
    It was found that the lower bainite of low volume fraction associated with lower-tempered martensite, had a very detrimental effect on the ductility. This could be due to the fact that crack initiation occured by brittle-fracture of bainite parallel to tensile axis as a result of higher plastic restraining the bainite by martensite during plastic deformation.
    When the upper bainite associated with the tempered martensite, a detrimental effect was found on the ductility regardless of volume fraction of bainite and tempering conditions. The detrimental effect results from the fact that, in low volume fraction of the bainite, crack initiation occurs by brittle-fracture of the bainite, and that with increase in the bainite, it occurs by brittle-fracture of martensite, it being attributable to higher stress concentration in the vicinity of two-phase interface as a result of unequal strain of two-phase at an earlier stage of plastic deformation.
  • 小野 清雄, 河野 富夫
    1978 年 64 巻 9 号 p. 1389-1395
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    Attempts have been made to clarify the chemical and electrochemical properties of inclusions in 18-8 stainless steel. To investigate the electrochemical property of inclusions, a method has been developed for measuring the polarization curve of a few mg weight of inclusions extracted from 18-8 stainless steel. The solubilities in water and 3% NaCl solutions and polarization curves in a 3% NaCl solution of the extracted α-MnS and MnSe containing a few percent of Fe and Cr were investigated.
    The sulfides dissolved greatly in aerated hot water and 3% NaCl solutions (pH≤4) while the selenides did not dissolve in aerated boiling water and 3% NaCl solution at pH 2. The polarization curves showed that the decomposition potential of the selenides was nobler than that of the sulfides. These results show that the selenides are more stable than the sulfides.
    Microscopic observations of 18-8 stainless steels containing sulfides or selenides in a 3% NaCl solution at pH 3 showed that the corrosion resistance of the steel containing stable selenides was superior to that of the steel containing less stable sulfides.
  • 渋谷 佳男, 遠藤 隆
    1978 年 64 巻 9 号 p. 1396-1403
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    This paper deals with the study of the high temperature oxidation behavior of borided steel and boride at various temperatures and time in air. The low carbon steel was used as the material and the immersion bonding was done with boric acid and potassium borate as sources of boron supply. In the case of heating at high temperature in air, the borided steel was expected to be resistant up to about 700°C while Fe2B fully existed. The apparent activation energy 25.1 kcal/mol was obtained for oxide formation of the boride Fe2 B in the temperature range from 700°C to 900°C in air. Surface boride Fe2 B changed as follows with the high temperature oxidation:
    Fe2B→Fe2B
    α-Fe→Fe2B
    α-Fe
    Fe-Oxide
    Fe-B-Oxide→Fe-Oxide
    Fe-B-Oxide
  • 高橋 良治, 佐藤 初吉, 吉村 照男, 飯島 一昭
    1978 年 64 巻 9 号 p. 1404-1413
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    This study has been made to improve fatigue strength of press-fitted parts of car axles by sub-critical quenching; water quenching from the temperature just below Ac1.
    The effect of sub-critical quenching on behaviours of fatigue crack propagation, the relation between σw2 (fatigue limit for failure) and sub-critical quenching temperature as well as the relation between hardness of ferrite structure and residual compressive stress at surface were investigated using notched specimens of 15mm in diameter (0.35%C steel) and are press-fitted specimens of 50 mm in diameter (0.4%C steel).
    Results obtained are as follows.
    (1) In sub-critical quenched specimens, both notched and press-fitted, fatigue cracks initiated and propagated to some extent and stopped, when the stress was applied above σw1 (fatigue limit for crack initiation) and below σw2. The crack length depended probably on the applied stress.
    (2) Maximum value of σw2 was obtained in the specimens, both notched and press-fitted, sub-critical quenched from about 650-750°C.
    (3) In the surface of sub-critical quenched specimens, hardness of ferrite structure was considerably increased. It was presumed that about 60% of total hardness increase was provided by age hardening after quenching, and about 40% of it by residual compressive stress generated on the surface by the quenching.
  • 森 康彦, 芦田 潮, 岸 輝雄, 堀内 良
    1978 年 64 巻 9 号 p. 1414-1423
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    The effect of pre-strain and low temperature annealing on the behaviours of Bauschinger effect was studied to establish the quantitative relation of yield stress decrease due to Bauschinger effect in rolled steel plates for welded structure. In this paper, Bauschinger strain and Bauschinger stress, which is a difference between applied stress and 0.1% proof stress in stress reversal, are used to indicate the amount of Bauschinger effect. The results are summarized as follows:
    (1) Both Bauschinger strain and stress increase with the increase of pre-strain, but the ratio of these indicators to the amount of strain hardening decreases rapidly with the amount of pre-strain and reaches constant at 2-3% pre-train.
    (2) The following relationship is well established between Bauschinger stress σB and pre-strain εP,
    σB=k·εmP
    where k and m are material constants.
    (3) The Bauschinger effect disappear gradually in low temperature annealing treatment. The activation energy of 18000-20000 cal/mol was obtained in the process, which means that the recovery process of Bauschinger effect is controlled by strain aging due to C and N solute atoms.
    (4) The back stress component which controls the Bauschinger effect was estimated. These values increase with pre-strain, however, they are about 30% of flow stress over the wide range of pre-strain.
    The pre-strain dependence of Bauschinger effect can be understood very well by the aspect of the back stresses.
  • 森山 和子, 合田 明弘, 針間矢 宣一
    1978 年 64 巻 9 号 p. 1424-1432
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
    Atomic absorption spectrometry with the HGA-2100 graphite furnace atomizer was used for the determination of aluminum greater than 0.0002% in iron and steel. Analytical sensitivity for aluminium was about ten times in comparison to that by the flame atomization method and the precision and accuracy were also satisfactory. Sample solution prepared by sulfuric acid decomposition was dried for 30 sec at 100°C, ashed for 60 sec at 1200°C, and atomized for 8 sec at 2700°C. The absorption signal at 309.3 nm was observed with a deuterium arc back ground corrector. Acid soluble aluminium of carbon steel and stainless steel was determined directly by an identical calibration curve without elimination of the bluk iron in sample solution. It was indispensable to use the standard addition method for the determination of acid insoluble aluminium to reduce the serious interferences due to coexisting elements in sample. Simple standard addition method, which is specific for the graphite furnace atomization, is especially recommended as a good method because sample solution volume for the measurement is very small and sample preparation is easy.
  • 藤村 理人
    1978 年 64 巻 9 号 p. 1433-1439
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
  • 内尾 高保
    1978 年 64 巻 9 号 p. 1440-1448
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
  • 濤崎 忍
    1978 年 64 巻 9 号 p. 1449-1456
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
  • 吉本 弘
    1978 年 64 巻 9 号 p. 1457-1467
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
  • 月橋 文孝, 高木 泰, 小林 一彦, 木下 勝雄, 郡司 好喜, 桜谷 敏和, 別所 永康, 野崎 努, 檀 武弘, 加藤 嘉英, 水上 ...
    1978 年 64 巻 9 号 p. 1475-1481
    発行日: 1978/08/01
    公開日: 2010/02/22
    ジャーナル フリー
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