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

Tetsu-to-Hagané Vol. 65 (1979), No. 12

  • Transactions ISIJに原著論文の寄稿を

    pp. 1661-1662

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    DOI:10.2355/tetsutohagane1955.65.12_1661

  • Transactions ISIJに原著論文の寄稿を

    pp. 1661-1662

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  • Investigation of the Influence of Alkali Circulation on the Blast Furnace Operation

    pp. 1663-1672

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    DOI:10.2355/tetsutohagane1955.65.12_1663

    This paper is concerned with the influence of alkali circulation on the degradation of coke and the blast furnaee operation.
    The adsorption rates of potassium on coke and sinter were measured experimentally as follows.
    υa, c=9.07e-16 900/RT. Pk (coke)
    υa, s= 0.68e-13 800/RT. Pk (sinter)
    where
    υa, c=adsorption rate on cokc (g/g-coke/min)
    υa, s=adsorption rate on sinter (g/g-sinter/min)
    Pk=partial pressure of potassium (atm)
    T = temperature (K)
    R=gas constant (cal/K/mol)
    Using these results, a mathematical model was developed with the assumption of the distribution of alkali in the blast furnace.
    The effect of alkali circulation on the blast furnace operation was investigated by using this model. The main results are summarized as follows:
    (1) Recycling alkali content increases as the slag basicity increases or the slag volume decreases.
    (2) The adverse effect of alkali in the coke ash on the alkali circulation, gasification and degradation of coke properties can be lowerd by charging high quality coke.
  • Investigation of the Influence of Alkali Circulation on the Blast Furnace Operation

    pp. 1663-1672

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    This paper is concerned with the influence of alkali circulation on the degradation of coke and the blast furnaee operation.
    The adsorption rates of potassium on coke and sinter were measured experimentally as follows.
    υa, c=9.07e-16 900/RT. Pk (coke)
    υa, s= 0.68e-13 800/RT. Pk (sinter)
    where
    υa, c=adsorption rate on cokc (g/g-coke/min)
    υa, s=adsorption rate on sinter (g/g-sinter/min)
    Pk=partial pressure of potassium (atm)
    T = temperature (K)
    R=gas constant (cal/K/mol)
    Using these results, a mathematical model was developed with the assumption of the distribution of alkali in the blast furnace.
    The effect of alkali circulation on the blast furnace operation was investigated by using this model. The main results are summarized as follows:
    (1) Recycling alkali content increases as the slag basicity increases or the slag volume decreases.
    (2) The adverse effect of alkali in the coke ash on the alkali circulation, gasification and degradation of coke properties can be lowerd by charging high quality coke.
  • The Softening Behavior under Load of Cold Bonded Pellets with Cement Binders

    pp. 1673-1682

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    DOI:10.2355/tetsutohagane1955.65.12_1673

    The softening behavior under load was investigated using cold bonded pellets with cement binders, made from iron ores of several types.
    In the case of cold bonded pellets, both the swelling and softening by reduction at elevating temperatures resulted in a big pressure drop in the softening test.
    The prevention of the swelling was effective when iron-silicate of low melting point was made from wustite and gangue minerals in a pellet particle in the temperature range from 900 to 1 100°C at which swelling usually took place to form slag net works.
    For the prevention of the softening, it was essential that the melting point of gangue minerals was transformed to higher levels.
    To satisfy both the requirements, iron-silicate of low melting point, bearing CaO, must be made in the temperature range from 900 to 1 100°C and transformed to Ca-silicate of high melting points by reduction above 1100°C.
    As the suitable composition of the cold bonded pellet including binders to meet the restriction, its gangue amount must be higher than 220 kg/t-Fe and its basicity (CaO/SiO) more than 1.2.
  • The Softening Behavior under Load of Cold Bonded Pellets with Cement Binders

    pp. 1673-1682

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    The softening behavior under load was investigated using cold bonded pellets with cement binders, made from iron ores of several types.
    In the case of cold bonded pellets, both the swelling and softening by reduction at elevating temperatures resulted in a big pressure drop in the softening test.
    The prevention of the swelling was effective when iron-silicate of low melting point was made from wustite and gangue minerals in a pellet particle in the temperature range from 900 to 1 100°C at which swelling usually took place to form slag net works.
    For the prevention of the softening, it was essential that the melting point of gangue minerals was transformed to higher levels.
    To satisfy both the requirements, iron-silicate of low melting point, bearing CaO, must be made in the temperature range from 900 to 1 100°C and transformed to Ca-silicate of high melting points by reduction above 1100°C.
    As the suitable composition of the cold bonded pellet including binders to meet the restriction, its gangue amount must be higher than 220 kg/t-Fe and its basicity (CaO/SiO) more than 1.2.
  • Effect of Molten Slag on the Dissolving Rate of Reduced Iron Pellets into Iron Melt

    pp. 1683-1691

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    DOI:10.2355/tetsutohagane1955.65.12_1683

    The effect of molten slag on iron melt upon the dissolving rate of cylindrical reduced iron pellets made from Höganäs iron powders, Fe2O3 powders and pulverized additives was investigated. The following results were obtained:
    (1) A small portion of iron oxide in pellets dissolved into the molten slag. The dissolving rate of pellets into iron melt was determined by neglecting the reduction of iron oxide in molten slag.
    (2) The maximum dissolving rate appeared at about unit basicity of molten slag. The effect of molten slag on the dissolving rate could be explained from their viscosity and density. The molten slag of the lower viscosity and the lower density would be desirable for higher dissolving rates.
    (3) The effect of molten slag with basicity of 0.5 and 1 on the temperature dependence of the dissolving rate into iron melt was small for pellets containing Fe2O3 and large for those without Fe2O3.
    (4) The molten slag with unit basicity had little effect on the dissolving rate of pellets containing CaO, CaCO3, C and flux (simultaneous addition of CaO and SiO2). The iron oxide which dissolved into the molten slag increased with increasing prefused slag, SiO2, and Al2O3 contents in pellets.
  • Effect of Molten Slag on the Dissolving Rate of Reduced Iron Pellets into Iron Melt

    pp. 1683-1691

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    The effect of molten slag on iron melt upon the dissolving rate of cylindrical reduced iron pellets made from Höganäs iron powders, Fe2O3 powders and pulverized additives was investigated. The following results were obtained:
    (1) A small portion of iron oxide in pellets dissolved into the molten slag. The dissolving rate of pellets into iron melt was determined by neglecting the reduction of iron oxide in molten slag.
    (2) The maximum dissolving rate appeared at about unit basicity of molten slag. The effect of molten slag on the dissolving rate could be explained from their viscosity and density. The molten slag of the lower viscosity and the lower density would be desirable for higher dissolving rates.
    (3) The effect of molten slag with basicity of 0.5 and 1 on the temperature dependence of the dissolving rate into iron melt was small for pellets containing Fe2O3 and large for those without Fe2O3.
    (4) The molten slag with unit basicity had little effect on the dissolving rate of pellets containing CaO, CaCO3, C and flux (simultaneous addition of CaO and SiO2). The iron oxide which dissolved into the molten slag increased with increasing prefused slag, SiO2, and Al2O3 contents in pellets.
  • On the Rate of the Reduction of Wustite, Magnetite, and Hematite Containing Al2O3, CaO, and MgO

    pp. 1692-1701

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    The effects of some foreign oxides on the rate limiting step of the reduction of pellets from wustite to metallic iron and the values of rate parameters are studied.
    It is confirmed that the reduction behavior of those pellets is represented by an unreacted core model or an uniform reaction model depending on the kinds of foreign oxides and iron oxides as starting materials. The mixed rate control equation of mass transfer in the gas phase, intraparticle gas diffusion, and chemical reaction can be applied to any iron oxide containing CaO and hematite and magnetite containing Al2O3. On the other hand, the reduction rate of the pure iron oxides, wustite containing Al2O3 and any iron oxides containing MgO is controlled by the oxygen diffusion in the metallic iron shell.
    These results are suggested by the conclusion of our previous studies that wustite grains are reduced nontopochemically and pellets are reduced topochemically when those complex oxides consisting of iron oxides and any foreign oxide precipitate in wustite during reduction.
  • On the Rate of the Reduction of Wustite, Magnetite, and Hematite Containing Al2O3, CaO, and MgO

    pp. 1692-1701

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    DOI:10.2355/tetsutohagane1955.65.12_1692

    The effects of some foreign oxides on the rate limiting step of the reduction of pellets from wustite to metallic iron and the values of rate parameters are studied.
    It is confirmed that the reduction behavior of those pellets is represented by an unreacted core model or an uniform reaction model depending on the kinds of foreign oxides and iron oxides as starting materials. The mixed rate control equation of mass transfer in the gas phase, intraparticle gas diffusion, and chemical reaction can be applied to any iron oxide containing CaO and hematite and magnetite containing Al2O3. On the other hand, the reduction rate of the pure iron oxides, wustite containing Al2O3 and any iron oxides containing MgO is controlled by the oxygen diffusion in the metallic iron shell.
    These results are suggested by the conclusion of our previous studies that wustite grains are reduced nontopochemically and pellets are reduced topochemically when those complex oxides consisting of iron oxides and any foreign oxide precipitate in wustite during reduction.
  • Influence of Alloying Elements on Uneven Solidification in Continuous Casting Mould

    pp. 1702-1711

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    The influence of alloying elements on uneven solidification in a continuous casting mould has been investigated by emptying unsolidified steel out of flat mould composed of water-cooled copper plate and sand. The following results are obtained:
    (1) In this experiment withou twithdrawal of strand and without use of powder, the solidified shell is formed as unevenly as in continuous casting mould, for specific alloying elements and contents.
    (2) In carbon steel, the unevenness of solidified shell has the maximum value at 0.11-0.13%C, and decreases rapidly when the carbon content deviates slightly away from this range. This tendency is the same as in longitudinal cracking of continuously cast slab.
    Also in SUS 304, Fe-11.6%Mn, Fe-10.1%Ni, and Fe-5.6% Si steels, the uneven solidification has been observed.
    (3) A formation model of the uneven solidification has been proposed. Namely, bending force towards liquid steel is potentially exerted at upper part of shell by the difference of amount of shrinkage between water-cooled copper plate side and liquid steel side of shell during solidifying and cooling. This force is encouraged by additional shrinkage accornpanying δ→γ transformation near solid-liquid interface of the shell. When high-temperature strength of shell is good and this force overcomes the ferrostatic pressure, the shell bends actually towards liquid steel and air gap is formed between the shell and mould. In this way, retardation of solidification is generated locally, and shell is formed unevenly.
  • Influence of Alloying Elements on Uneven Solidification in Continuous Casting Mould

    pp. 1702-1711

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    DOI:10.2355/tetsutohagane1955.65.12_1702

    The influence of alloying elements on uneven solidification in a continuous casting mould has been investigated by emptying unsolidified steel out of flat mould composed of water-cooled copper plate and sand. The following results are obtained:
    (1) In this experiment withou twithdrawal of strand and without use of powder, the solidified shell is formed as unevenly as in continuous casting mould, for specific alloying elements and contents.
    (2) In carbon steel, the unevenness of solidified shell has the maximum value at 0.11-0.13%C, and decreases rapidly when the carbon content deviates slightly away from this range. This tendency is the same as in longitudinal cracking of continuously cast slab.
    Also in SUS 304, Fe-11.6%Mn, Fe-10.1%Ni, and Fe-5.6% Si steels, the uneven solidification has been observed.
    (3) A formation model of the uneven solidification has been proposed. Namely, bending force towards liquid steel is potentially exerted at upper part of shell by the difference of amount of shrinkage between water-cooled copper plate side and liquid steel side of shell during solidifying and cooling. This force is encouraged by additional shrinkage accornpanying δ→γ transformation near solid-liquid interface of the shell. When high-temperature strength of shell is good and this force overcomes the ferrostatic pressure, the shell bends actually towards liquid steel and air gap is formed between the shell and mould. In this way, retardation of solidification is generated locally, and shell is formed unevenly.
  • The Rate of Oxygen Absorption of Liquid Iron

    pp. 1712-1719

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    DOI:10.2355/tetsutohagane1955.65.12_1712

    The process of oxygen absorption of liquid iron has been studied by taking the formation of iron oxide at the gas-metal interface into account. The rates of oxygen absorption have been measured by blowing Ar-O2 gas mixtures onto inductively stirred liquid iron.
    It was confirmed that oxygen absorption from gas phase is represented by a model that most of gaseous oxygen dissolves into liquid iron through oxide free interface, although some of them forms iron oxide at the interface and then dissolves into liquid iron. The results show that this model is valid for the process of oxygen absorption in the range above 0.057 atm pO2· When the partial pressure of oxygen is lower than 0.057atm pO2, however, the formation of oxide could be practically ignored, so that the rate of oxygen absorption is controlled simply by the mass transfer in gas phase.
  • The Rate of Oxygen Absorption of Liquid Iron

    pp. 1712-1719

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    The process of oxygen absorption of liquid iron has been studied by taking the formation of iron oxide at the gas-metal interface into account. The rates of oxygen absorption have been measured by blowing Ar-O2 gas mixtures onto inductively stirred liquid iron.
    It was confirmed that oxygen absorption from gas phase is represented by a model that most of gaseous oxygen dissolves into liquid iron through oxide free interface, although some of them forms iron oxide at the interface and then dissolves into liquid iron. The results show that this model is valid for the process of oxygen absorption in the range above 0.057 atm pO2· When the partial pressure of oxygen is lower than 0.057atm pO2, however, the formation of oxide could be practically ignored, so that the rate of oxygen absorption is controlled simply by the mass transfer in gas phase.
    x

    Readers Who Read This Article Also Read

    1. Heat Transfer Phenomena in Immersion Cooling of Heated Steel Plate and Influence of Water Stirring on Heat Transfer Tetsu-to-Hagané Vol.64(1978), No.1
    2. 第97回講演大会討論会講演概要 Tetsu-to-Hagané Vol.65(1979), No.2
    3. 第95回講演大会討論会講演概要 Tetsu-to-Hagané Vol.64(1978), No.2
  • On the Rates of Oxygen Absorption of Liquid Fe-Cr and Fe-Cr-Ni Alloys

    pp. 1720-1726

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    DOI:10.2355/tetsutohagane1955.65.12_1720

    The rates of oxygen absorption of liquid Fe-18Cr, Fe-18Cr-8Ni and Fe-25Cr-20Ni alloys from O2-Ar and CO2-Ar gas mixtures have been measured. The initial rate of oxygen absorption is proportional to the partial pressure of oxygen or carbon dioxide, independently of alloy and gas mixture compositions. The results agree with those of liquid iron obtained in the stream of O2-Ar gas mixtures. The oxygen absorption of those alloys is simulated by the same model applied to the oxygen absorption of liquid iron, when the partial pressure of oxygen or carbon dioxide is higher than 0.003 atm. Accordingly, it is probable that most of gaseous oxygen dissolve into liquid phase through the oxide free interface, although some of them are transfered by the dissolution of oxide formed at the gas-metal interface. Furthermore, the amount of oxygen accumulated at the interface as oxide phase should be larger than that in liquid iron under the same oxygen potential.
    When the initial carbon concentration in melts is somewhat high, the oxygen absorption accompanying decarburization is significant even under the condition that the rate of decarburization is controlled by the mass transfer of oxidizing gas.
  • On the Rates of Oxygen Absorption of Liquid Fe-Cr and Fe-Cr-Ni Alloys

    pp. 1720-1726

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    The rates of oxygen absorption of liquid Fe-18Cr, Fe-18Cr-8Ni and Fe-25Cr-20Ni alloys from O2-Ar and CO2-Ar gas mixtures have been measured. The initial rate of oxygen absorption is proportional to the partial pressure of oxygen or carbon dioxide, independently of alloy and gas mixture compositions. The results agree with those of liquid iron obtained in the stream of O2-Ar gas mixtures. The oxygen absorption of those alloys is simulated by the same model applied to the oxygen absorption of liquid iron, when the partial pressure of oxygen or carbon dioxide is higher than 0.003 atm. Accordingly, it is probable that most of gaseous oxygen dissolve into liquid phase through the oxide free interface, although some of them are transfered by the dissolution of oxide formed at the gas-metal interface. Furthermore, the amount of oxygen accumulated at the interface as oxide phase should be larger than that in liquid iron under the same oxygen potential.
    When the initial carbon concentration in melts is somewhat high, the oxygen absorption accompanying decarburization is significant even under the condition that the rate of decarburization is controlled by the mass transfer of oxidizing gas.
  • Permeabilities of Oxygen through Molten CaO-SiO2-Al2O3 System with Fe2O3 or CaF2

    pp. 1727-1736

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    DOI:10.2355/tetsutohagane1955.65.12_1727

    The permeabilities of oxygen through the molten Fe2O3-CaO-SiO2-Al2O3and CaF2-CaO-SiO2-Al2O3systems were measured by means of an experimental procedure which was developed by the authors. Those trough the Fe2O3-CaO-SiO2-Al203and CaF2-CaO-SiO2-Al2O3melts were found to be in the range of 1×10-8to 1×10-6and 5×10-12to 5×10-8moles O2/cm·s, respectively. The permeability was raised by a factor of 10 to the 10th power when 0.2 wt% of Fe2O3was added to 40 wt%CaO-40 wt%SiO2-20 wt% Al2O3melt. The permeabilities through the molten slags with Fe2O3are proportional to the 1/4th power of oxygen partial pressure in the atmosphere. The permeabilities through the molten slags without Fe2O3are directly proportional to the oxygen partial pressure in the atmosphere. They increase when CaF2is added to the Fe2O3-CaO-SiO2-Al2O3melt.
  • Permeabilities of Oxygen through Molten CaO-SiO2-Al2O3 System with Fe2O3 or CaF2

    pp. 1727-1736

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    The permeabilities of oxygen through the molten Fe2O3-CaO-SiO2-Al2O3and CaF2-CaO-SiO2-Al2O3systems were measured by means of an experimental procedure which was developed by the authors. Those trough the Fe2O3-CaO-SiO2-Al203and CaF2-CaO-SiO2-Al2O3melts were found to be in the range of 1×10-8to 1×10-6and 5×10-12to 5×10-8moles O2/cm·s, respectively. The permeability was raised by a factor of 10 to the 10th power when 0.2 wt% of Fe2O3was added to 40 wt%CaO-40 wt%SiO2-20 wt% Al2O3melt. The permeabilities through the molten slags with Fe2O3are proportional to the 1/4th power of oxygen partial pressure in the atmosphere. The permeabilities through the molten slags without Fe2O3are directly proportional to the oxygen partial pressure in the atmosphere. They increase when CaF2is added to the Fe2O3-CaO-SiO2-Al2O3melt.
  • Classification of Numerical Methods for Transient Heat Transfer Problem and Improved Inner Nodal Point Method

    pp. 1737-1746

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    DOI:10.2355/tetsutohagane1955.65.12_1737

    A proposal has been made for the classification of numerical methods to two groups; one is based on a differential equation and the other is not. The latter “Direct Method”, which means that a finite-difference equation is derived directly from the phenomenon, may be divided into Outer and Inner Nodal Point Methods (ONP Method and INP Method). The typical ONP Method is the matrix method developed by the authors, where the nodal point is designated on the element boundary. In the INP Method the nodal point is designated within the element and the nodal domain is the element itself. On the basis of this classification and some discussion on the conventional methods, an improved INP Method has been developed and the outline with finite-difference equations for energy balance, mass balance and momentum equations for potential flow is presented. In addition, numerical examples for solidification problems are demonstrated and discussed. Although the combination of right triangle elements forming a rectangle can not be used in the proposed method, it has the same advantage as the ONP Method over the conventional finite element method and is superior to the ONP Method in simplicity and computing time.
  • Classification of Numerical Methods for Transient Heat Transfer Problem and Improved Inner Nodal Point Method

    pp. 1737-1746

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    A proposal has been made for the classification of numerical methods to two groups; one is based on a differential equation and the other is not. The latter “Direct Method”, which means that a finite-difference equation is derived directly from the phenomenon, may be divided into Outer and Inner Nodal Point Methods (ONP Method and INP Method). The typical ONP Method is the matrix method developed by the authors, where the nodal point is designated on the element boundary. In the INP Method the nodal point is designated within the element and the nodal domain is the element itself. On the basis of this classification and some discussion on the conventional methods, an improved INP Method has been developed and the outline with finite-difference equations for energy balance, mass balance and momentum equations for potential flow is presented. In addition, numerical examples for solidification problems are demonstrated and discussed. Although the combination of right triangle elements forming a rectangle can not be used in the proposed method, it has the same advantage as the ONP Method over the conventional finite element method and is superior to the ONP Method in simplicity and computing time.
    x

    Readers Who Read This Article Also Read

    1. Heat Transfer Phenomena in Immersion Cooling of Heated Steel Plate and Influence of Water Stirring on Heat Transfer Tetsu-to-Hagané Vol.64(1978), No.1
    2. 第97回講演大会討論会講演概要 Tetsu-to-Hagané Vol.65(1979), No.2
    3. 第95回講演大会討論会講演概要 Tetsu-to-Hagané Vol.64(1978), No.2
  • Formation of Transformation Texture in Controlled Rolled Steels

    pp. 1747-1755

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    DOI:10.2355/tetsutohagane1955.65.12_1747

    The formation of the transformation textures has been studied in low C-Mn-Nb-V and low C-Mn-Mo-Nb steels which were subjected to deformation in unrecrystallized austenite region. Using the method of crystallite orientation distribution function analysis, textures were quantitatively determined in as-rolled and as-quenched steels with polygonal ferrite-pearlite or acicular ferrite or martensite which were produced by an experimentally controlled rolling process. Transformation textures develop markedly by deforming austenite phase in unrecrystallized austenite region. The textures consist of two preferred orientations; {113} <110> and {332} <113>. The density of these orientations, especially {332} <113> in both acicular ferrite and martensite steels are greater than that in polygonal ferrite-pearlite steel. The orientation density of {332} <113> in both steels increases with decreasing prior austenitic grain size. Crystallite orientation distributions after transformation of austenite having (110) [112], (641) [112], (321) [214], and (211) [111] were calculated for polygonal ferrite-pearlite and martensite steels. It was as sumed that the austenite to polygonal ferrite transformation followed the Kurdjumov-Sachs lattice orientation relationship and that all the variants were operative during the transformation. While, in the case of the austenite to martensite transformation, such variants were assumed to operate that corresponded to the slip systems with the largest resolved shear stress in the slip deformation of anstenite phase. These calculated crystallite orientation distributions are in good agreement with observed results. The formation of the transformation texture of acicular ferrite steel seems to be similar to that of martensite steel.
  • Formation of Transformation Texture in Controlled Rolled Steels

    pp. 1747-1755

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    The formation of the transformation textures has been studied in low C-Mn-Nb-V and low C-Mn-Mo-Nb steels which were subjected to deformation in unrecrystallized austenite region. Using the method of crystallite orientation distribution function analysis, textures were quantitatively determined in as-rolled and as-quenched steels with polygonal ferrite-pearlite or acicular ferrite or martensite which were produced by an experimentally controlled rolling process. Transformation textures develop markedly by deforming austenite phase in unrecrystallized austenite region. The textures consist of two preferred orientations; {113} <110> and {332} <113>. The density of these orientations, especially {332} <113> in both acicular ferrite and martensite steels are greater than that in polygonal ferrite-pearlite steel. The orientation density of {332} <113> in both steels increases with decreasing prior austenitic grain size. Crystallite orientation distributions after transformation of austenite having (110) [112], (641) [112], (321) [214], and (211) [111] were calculated for polygonal ferrite-pearlite and martensite steels. It was as sumed that the austenite to polygonal ferrite transformation followed the Kurdjumov-Sachs lattice orientation relationship and that all the variants were operative during the transformation. While, in the case of the austenite to martensite transformation, such variants were assumed to operate that corresponded to the slip systems with the largest resolved shear stress in the slip deformation of anstenite phase. These calculated crystallite orientation distributions are in good agreement with observed results. The formation of the transformation texture of acicular ferrite steel seems to be similar to that of martensite steel.
    x

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  • Tensile and Fatigue Properties of Austenitic Stainless Steels at LNG Temperature

    pp. 1756-1765

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    DOI:10.2355/tetsutohagane1955.65.12_1756

    Tensile strength, fatigue strength and fatigue crack growth rate of metastable and stable austenitic stainless steels at the temperatures between 20°C and ·162°C have been studied. Microstructural changes of specimens during tensile and fatigue deformation were also observed. The results obtained are as follows.
    1) The proof stress of metastable steels slightly drops at low temperatures below about -100°C. This is due to the inducement of ε-martensite by tensile stress. Addition of nitrogen makes austenite matrix stable and rises proof stress.
    2) The fatigue strength increases with the increase in tensile strength which is raised by the inducement of α′-martensite in metastable steels and by the solid solution strengthening of matrix due to the addition of nitrogen in stable ones.
    3) Microstructural changes of tensile and fatigue deformation are characterized by α′-phase formation in metastable steel and by planar arrays of dislocation pile-ups in nitrogen added stable steel at-162°C.
    4) At-162°C, fatigue crack growth rate in high ΔK region is larger in metastable steels than in stable ones. This will be attributed to the formation of α′-phase at the tip of crack. In low ΔK region, stable steels exhibit large crack growth rate and this is due to a rapid propagation of fatigue crack along the slip line.
  • Tensile and Fatigue Properties of Austenitic Stainless Steels at LNG Temperature

    pp. 1756-1765

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    Tensile strength, fatigue strength and fatigue crack growth rate of metastable and stable austenitic stainless steels at the temperatures between 20°C and ·162°C have been studied. Microstructural changes of specimens during tensile and fatigue deformation were also observed. The results obtained are as follows.
    1) The proof stress of metastable steels slightly drops at low temperatures below about -100°C. This is due to the inducement of ε-martensite by tensile stress. Addition of nitrogen makes austenite matrix stable and rises proof stress.
    2) The fatigue strength increases with the increase in tensile strength which is raised by the inducement of α′-martensite in metastable steels and by the solid solution strengthening of matrix due to the addition of nitrogen in stable ones.
    3) Microstructural changes of tensile and fatigue deformation are characterized by α′-phase formation in metastable steel and by planar arrays of dislocation pile-ups in nitrogen added stable steel at-162°C.
    4) At-162°C, fatigue crack growth rate in high ΔK region is larger in metastable steels than in stable ones. This will be attributed to the formation of α′-phase at the tip of crack. In low ΔK region, stable steels exhibit large crack growth rate and this is due to a rapid propagation of fatigue crack along the slip line.
  • Etch-Pattern of Transverse Cross-Section and Ridging Phenomenon in 18Cr Stainless Steel Sheet

    pp. 1766-1773

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    The correspondence of the unduration of ridging after tensile test to that of microscopic etch-pattern due to the segregation of Cr and C in 18% Cr cold rolled and annealed stainless steel sheet was observed. The results are as follows.
    (1) A laminated etch-pattern is observed at the center layer of transverse cross-section of hot rolled band. This laminated etch-pattern becomes wavy and is observed in the full-thickness of cold rolled and annealed sheet.
    (2) The unduration of wavy etch-pattern nearly corresponds to that of ridging appeared after stretching the specimen to its rolling direction by 20%.
    (3) The height of unduration of ridging is proportional to that of wavy etch-pattern.
    (4) These facts suggest that the wavy etch-pattern to be the origin of ridging phenomenon in this steel sheet.
    x

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  • Etch-Pattern of Transverse Cross-Section and Ridging Phenomenon in 18Cr Stainless Steel Sheet

    pp. 1766-1773

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    DOI:10.2355/tetsutohagane1955.65.12_1766

    The correspondence of the unduration of ridging after tensile test to that of microscopic etch-pattern due to the segregation of Cr and C in 18% Cr cold rolled and annealed stainless steel sheet was observed. The results are as follows.
    (1) A laminated etch-pattern is observed at the center layer of transverse cross-section of hot rolled band. This laminated etch-pattern becomes wavy and is observed in the full-thickness of cold rolled and annealed sheet.
    (2) The unduration of wavy etch-pattern nearly corresponds to that of ridging appeared after stretching the specimen to its rolling direction by 20%.
    (3) The height of unduration of ridging is proportional to that of wavy etch-pattern.
    (4) These facts suggest that the wavy etch-pattern to be the origin of ridging phenomenon in this steel sheet.
  • Multiplicative Interferences of Coexistent Elements on Emission Spectrochemical Analysis in Steel

    pp. 1774-1779

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    DOI:10.2355/tetsutohagane1955.65.12_1774

    Interference effects of coexisting elements on emission spectrochemical analysis for steel were studied. Binary (Fe-X) and ternary (Fe-X-Y) samples made with Ar-Arc furnace were used for experiments. The effects of C, Mn, Ni, Cr, and Mo on S, of Si, Mn, Cr, and Mo on Nb, of Mn, Cu, Ni, Cr, and Mo on P, and of Mn, Ni, Cr, and Mo on V were investigated. In many cases interference effects were due to the neighbouring line of coexisting element. Multiplicative interference was observed between S and C, and between Nb and Mo, and the difference between obtained values and the values certified by chemical analysis were expressed as follows: ΔS=f (C, S), ΔNb=f (Nb, Mo). The approximation correction method to correct the difference caused by the multiplicative interference was proposed and applied to routine analysis. It is indicative from this study that the unification of calibration curves can be made, regardless of materials which were subjected to different metallurgical treatments.
  • Multiplicative Interferences of Coexistent Elements on Emission Spectrochemical Analysis in Steel

    pp. 1774-1779

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    Interference effects of coexisting elements on emission spectrochemical analysis for steel were studied. Binary (Fe-X) and ternary (Fe-X-Y) samples made with Ar-Arc furnace were used for experiments. The effects of C, Mn, Ni, Cr, and Mo on S, of Si, Mn, Cr, and Mo on Nb, of Mn, Cu, Ni, Cr, and Mo on P, and of Mn, Ni, Cr, and Mo on V were investigated. In many cases interference effects were due to the neighbouring line of coexisting element. Multiplicative interference was observed between S and C, and between Nb and Mo, and the difference between obtained values and the values certified by chemical analysis were expressed as follows: ΔS=f (C, S), ΔNb=f (Nb, Mo). The approximation correction method to correct the difference caused by the multiplicative interference was proposed and applied to routine analysis. It is indicative from this study that the unification of calibration curves can be made, regardless of materials which were subjected to different metallurgical treatments.
  • Development of On-Line Analysis System for Components in Plating Bath and Some Chemical Treatment Baths of Electric Galvanizing Process

    pp. 1780-1786

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    DOI:10.2355/tetsutohagane1955.65.12_1780

    The fundamental approaches for an automatic concentration control system were made of five kinds of chemical treatment baths in an electric galvanizing process. The results obtained are summarized as follows: (1) The concentration of NaOH or Na4SiO4 in an alkali-using cleaning bath and H2SO4 in a pickling bath can be analized with electric conductivity cell. (2) The concentration of ZnSO4·7H2O and H2SO4 in an electric galvanizing bath can be automatically analyzed with the combination of specific gravity meter and pH meter. (3) The concentration of (NH4) 2CO3 in an electolytic cleaning bath can be automatically analyzed with electric conductivity cell and those of CrO3 and its addition in an electrolytic chromate bath can be done with the combination of electric conductivity cell and specific gravity meter.
  • Development of On-Line Analysis System for Components in Plating Bath and Some Chemical Treatment Baths of Electric Galvanizing Process

    pp. 1780-1786

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    The fundamental approaches for an automatic concentration control system were made of five kinds of chemical treatment baths in an electric galvanizing process. The results obtained are summarized as follows: (1) The concentration of NaOH or Na4SiO4 in an alkali-using cleaning bath and H2SO4 in a pickling bath can be analized with electric conductivity cell. (2) The concentration of ZnSO4·7H2O and H2SO4 in an electric galvanizing bath can be automatically analyzed with the combination of specific gravity meter and pH meter. (3) The concentration of (NH4) 2CO3 in an electolytic cleaning bath can be automatically analyzed with electric conductivity cell and those of CrO3 and its addition in an electrolytic chromate bath can be done with the combination of electric conductivity cell and specific gravity meter.
  • Properties and Utilization of Ironmaking and Steelmaking Slags

    pp. 1787-1811

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    DOI:10.2355/tetsutohagane1955.65.12_1787

  • Properties and Utilization of Ironmaking and Steelmaking Slags

    pp. 1787-1811

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  • Estimation of Optimum Lance Height at Intermediate Stage in LD Converter Operation

    pp. 1812-1813

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  • Estimation of Optimum Lance Height at Intermediate Stage in LD Converter Operation

    pp. 1812-1813

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    DOI:10.2355/tetsutohagane1955.65.12_1812

  • ドイツクラウスタール大学の思い出

    pp. 1814-1815

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    DOI:10.2355/tetsutohagane1955.65.12_1814

  • ドイツクラウスタール大学の思い出

    pp. 1814-1815

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  • 抄録

    pp. 1816-1820

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  • 抄録

    pp. 1816-1820

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    DOI:10.2355/tetsutohagane1955.65.12_1816

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