Tetsu-to-Hagané
New Arrival Alert : OFF

You can use this feature after you logged into the site.
Please click the button below.

Log in / Sign up
ONLINE ISSN: 1883-2954
PRINT ISSN: 0021-1575

Tetsu-to-Hagané Vol. 81 (1995), No. 8

  • Dependence of Flow Stress of Steels at Elevated Temperature on the Content of Micro Alloying Elements

    pp. 773-779

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    [in Japanese]
  • Measurement of Calcium Contents in Molten Nickel by Using Oxygen Sensor with Auxiliary Electrode

    pp. 780-785

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    A sensor to determine calcium contents in molten metal is examined. The sensor is constituted of an oxygen sensor with an auxiliary electrode which is surrounded with a cap made of silica. 0.02 to 0.1 mass% of calcium contents in molten nickel can be detected by the sensor. Relation between calcium contents in the molten nickel and electromotive forces of the sensor can be expressed as following equation :
    EMF/mV= -173log [%Ca] -423 ± 18
    According to discussion on the basis of thermochemistry, it is revealed that the sensor acts as a chemical sensor of which output is determined by the thermochemical relation between calcium and oxygen.
  • Thermodynamics of Ni-Mg-O and Ni-Nb-Mg-O Melts in Equilibrium with Solid MgO

    pp. 786-791

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    The deoxidation equilibrium of magnesium in liquid nickel and nickel-niobium alloys has been measured at the temperature ranges from 1873 to 1973 K and 1873 K respectively, by the use of magnesia crucible with a view to understanding the equilibrium between magnesium and oxygen, and the effect of niobium on the activity coefficients of oxygen and magnesium in liquid nickel.
    For the deoxidation reaction in pure liquid nickel, i.e. :
    MgO(s)=Mg+O
    the effect of the temperature on the equilibrium constant, KMg(Ni) ( =aMg·ao/aMgO), was found to be :
    log KMg(Ni)=-25500/T + 7.78
    while the effect of magnesium on the activity coefficient of oxygen in liquid nickel was expressed to be :
    logfMgO(Ni) = (-126300/T + 39.0)[%Mg] 0.003<[%Mg]<0.07
    The deoxidation equilibrium of magnesium in liquid nickel-niobium alloys with 0.005-0.042 mass% magnesium has been measured up to 8 mass% niobium. The activity coefficients of magnesium and oxygen in liquid nickel-niobium alloys were given by the expression :
    logfNbO(Ni) + logfNbMg(Ni) = -0.12[%Nb] [%Nb]<8
  • Characteristics of Embrittlement of Continuously Cast Steel near the Solidification Temperature

    pp. 792-797

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    Tensile strength, ductility and sensitivity of internal crack formation of specimens sampled from continuously cast slabs and experimentaly cast small scale ingots were measured up to their solidification temperature by tensile tests. In the case of experimentaly cast ingots, manganese and sulphur contents were changed widely.
    The results obtained are summarized as follows.
    (1) In the brittle region, the tensile strength is below 1kg/mm2 and the apparent elastic modulus is about 100-200kg/ mm2.
    (2) The brittle-ductile transition mainly depends on the existence of residual (Mn, Fe) S liquid film along the dendritic interface.
    (3) The critical strain for internal crack formation varies from zero at ZST (Zero Strength Temperature) to about 1% at ZDT (Zero Ductility Temperature) in the brittle region and is found to be independent of strain rate or carbon contents. It was thought that these results come from the lack of molten metal in front of the crack in this tensile tests. On the contrary, it was suggested that the healing behavior of molten metal at the solidification front concerns to the crack formation in real steel strand.
  • Analyzing Chatter Marks on Cold Rolling Strips and Countermeasure

    pp. 798-802

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    Recently, higher quality of the surface of cold rolling strip has been demanded. As a result, the quality level which was satisfactory before is not now. In particular, we need higher quality flat plate in order to produce a better gloss and mirror pattern for the outside plate of the car and wall plate.
    Therefore, we investigated a relation between the vibration of machine and that of steel sheet in order to explain the source of chatter marks, which can be found only by skilled inspector. As a result it is confirmed that chatter marks which are generated by skin pass mill and tension leveler are resonance phenomena which arises due to the natural frequencies of the roll and the roll drive system as well as that of the transverse oscillation of steel sheet. To surpress the chatter marks, it is necesarry to control the vibration of the roll and the side walls.
  • Control of Duplex Grain Structure at Edge of Hot Rolled Steel Sheets

    pp. 803-808

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    The conditions which prevent the occurrence of duplex grain structure of hot rolled steel sheets have been studied by using a model which can predict the strain induced transformation of ferrite from hot worked austenite. The obtained results are the following.
    The occurrence of duplex grain structure depends upon the temperature schedule during finish rolling and it occurs in case that the sum of the consumption of fractional incubation time becomes 1.0 before the last reduction of finish rolling. The critical temperature for preventing the duplex grain structure reduces with increasing C and Mn, reducing the strip thickness and decreasing the rolling speed. The close agreement between these tendencies and the values calculated by a newly developed model to prevent the duplex grain structure has been obtained. On the basis of these results, a control technique of edge heating machine for preventing the duplex grain structure has been developed.
  • Effect of Surface Roughness of Mother Sheet on Occurrence of Oil-pit in Cold Rolling for SUS430 Sheet

    pp. 809-814

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    To produce cold rolled stainless steel sheets efficiently in high speed rolling, surface brightness must be improved. The surface brightness of the sheets is strongly affected by oil-pits which occur on the surface of the sheets in cold rolling. As the number of oil-pits decreases, the surface brightness of the sheets is improved.
    In this study, the morphology of oil-pits in actual cold rolling is observed by a microscope and SEM (Scanning Electron Microscopy). The effect of the surface roughness of the mother sheet on the occurrence of oil-pits in cold rolled sheet is examined with a laboratory-scale rolling mill.
    The results obtained are as follows :
    (1) Oil-pits occur at the bottom of micro-pits on the surface of the mother sheet, at the bottom of scratches which are marks due to the surface roughness of rolls and in the flat surface around the micro-pits and the scratches.
    (2) It can be explained that oil pits in the flat surfaces around micro-pits are formed by the squeezing of rolling oil from the micro-pits.
    (3) It can be explained that oil-pits at the bottom of the micro-pits and the scratches are caused by enclosure of rolling oil in the micro-pits and the scratches.
  • Thermodynamic and Morphlogical Investigations of Dross in Molten Zn Bath

    pp. 815-820

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    A study was conducted on the formation of Zn-Fe and Fe-Al crystals in a molten Zn bath. Baths similar in composition to that of a CGL, were prepared in the laboratory and attention was paid on the cooling rate in Zn bath sampling.
    When samples were cooled at lower cooling rates than 100°C/s, crystallization and crystal growth were observed in the Zn bath sample ingots. Higher cooling rates than 105°C/s inhibited the crystallization and crystal growth during cooling. In order to evaluate the presence of crystals in the Zn bath, it is necessary to employ a rapid cooling.
    The type of crystal changed with the Al content of the bath. In a bath containing above 0.13mass% Al, Fe2Al5 formed. Below 0.13mass%, FeZn7, formed. From the results obtained with the rapid cooling technique, an equilibrium solubility curve for Fe and Al was estimated in the region where Fe2Al5 was crystallized. The curve was expressed as Log [Fe]2[Al]5=5.37-9354/T for Fe+5/2Al=1/2Fe2Al5. With this equation, the available Zn-Al-Fe ternary phase diagram in the literature was corrected at the Zn corner.
    x

    Readers Who Read This Article Also Read

    1. Identification of the Fe-Zn Intermetallic Phases by TEM Tetsu-to-Hagané Vol.83(1997), No.5
    2. Reactive Diffusion between Solid Fe and Liquid Zn at 723 K ISIJ International Vol.47(2007), No.5
  • Effect of Minute Solute Elements in the Ferrite Matrix on the Inherent Creep Strength of Carbon Steels

    pp. 821-826

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    One of the present authors has proposed a new concept about the Inherent creep strength determining the long term creep strength of ferritic steels. In the present study, effect of solute elements in the ferrite matrix on the Inherent creep strength of 0.2 and 0.3 mass% carbon steels was studied from a view point of atomic configurations such as atomic pairs. The equilibrium concentrations of solute elements and atomic pairs in the ferrite matrix were estimated by thermodynamic calculations with the sublattice model (Thermo-calc.) and the central atoms model, respectively. The following results are obtained; (1) The Inherent creep strength of carbon steels at 773K and 88MPa is proportional to concentrations of Mn and Mo in the ferrite and inversely proportional to those of C and Si. (2) A good correlation is observed between the Inherent creep strength and the concentrations of Mn-C and Mo-C atomic pairs. These atomic pairs seem to reduce the climb velocity of dislocations due to their large interaction energies with dislocations. Thus, it is concluded that the Inherent creep strength of carbon steels is controlled by Mn-C and Mo-C atomic pairs in the ferrite matrix.
  • Effect of Crevice on Low Cycle Fatigue Behavior of Pressure Vessel Steel in High Temperature Pressurized Water

    pp. 827-832

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    The effect of crevice on low cycle fatigue behavior of a low alloy steel JIS SQV2A (equivalent to ASTM A533B cl. 1) for reactor pressure vessel was investigated in high temperature pressurized water at 561K and 7.8Mpa. Crevice were made on the specimen surface by attaching a pair of split collars of the same material. The dissolved oxygen (DO) concentration was varied from 10 ppb to 4000 ppb.
    The fatigue life was found longer for creviced specimens than that for no creviced ones, especially for low strain range. The same trend was observed at low DO concentration levels. In case of no creviced specimen, fatigue life was notably reduced for DO concentrations higher than 1000ppb.
    It can be concluded that the extention of fatigue life of the creviced specimens is due to the reduction of DO concentraion in the crevice.
  • Effects of Mn and Mo Contents 1 Cr Steel Powders on Compressibility and Tensile Strength of Their Sintered Compact

    pp. 833-838

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    A prealloy steel powder which was Mn-less, contained 1Cr-0.3Mo and low oxygen was developed to improve compressibility of steel powder, tensile strength and toughness of sintered compact.
    This newly developed steel powder showed high compressibility of green density of 7.15Mg/m3 at 690MPa of compacting pressure. This is derived from the decrease in solution hardening effect and Mn oxide on powder surface with decrease in Mn content.
    The sintered compacts made from the new powder with 0.9% graphite addition gave a tensile strength of 900MPa and a Charpy absorbed energy of 17J, when compacted at 690MPa and sintered at 1150°C. These values were higher by 200MPa and 3J, respectively, than those of compacts made from a conventional 1Cr-0.3 Mo-0.7 Mn steel powder.
    The strength and toughness improved, respectively, because of the production of fine pearlite structure and the decrease in Mn oxide with decrease in Mn content.
  • Creep Behavior Analysis of a Service-exposed 2.25Cr-1Mo Steel

    pp. 839-844

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    For the remaining creep life assessment, it is essential to evaluate the degree of structural degradation. In the present study, accelerated creep tests have been employed to assess the degree of structural deterioration of a 2.25 Cr-1Mo steel which was service-exposed for 11 years as a power plant component. The experimental results showed that strain rate over a wide rage of strain is expressed by the equation; lnε =lnε0+Sε, where ε0 is the imaginary initial creep rate and S is the strain rate acceleration factor. The magnitudes of ε0 and S are given by the following equations; ε0=A0σ0nexp(-Q0/RT). and S=Asσ0-nsexp(Qs/RT), where A0 is the mechanically defined structure factor, σ0 is the initial stress, n is the stress exponent (9.5), Q0 is the activation energy (429 kJ/mol), Qs is 24kJ/mol, As is a constant, and ns is 0.98. Comparing these results with those of prestrained materials, it was found that the magnitudes of A0, As and ns are dependent upon the structural deterioration while those of n, Q0 and Qs are independent of thermo-mechanical history. This means that the rate controlling mechanism is independent of structural deterioration. These historydependent parameters allow us the quantitative assessment of the structural deterioration of service-exposed materials.
  • Effect of Cold-rolling on Creep Behavior of a 10Cr-30Mn Austenitic Steel

    pp. 845-850

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    The effect of cold-rolling on creep deformation has been investigated for 10Cr-30Mn austenitic steels containing 0.003, 0.11 and 0.55 mass% carbon. After 20% cold-rolling at room temperature, the specimens were subjected to creep test at 873K for up to about 10000h. The test results were compared with those of solution-annealed specimens. The cold -rolling caused a decrease in minimum creep rate εmin and an increase in time to rupture tr at high stresses and short times. At low stresses and long times, however, the effect of cold-rolling on the εmin and tr depended on carbon concentration and test duration. The tr of the specimens was described by tr=1.45/(εmin·Ωp), where, Ωp is the creep damage parameter given by Ωp=dlnε/dε. Both the εmin and Ωp are correlated with the microstructural evolution during creep, such as the precipitation of σ phase, M23C6 and the recrystallization of deformed grains produced by cold-rolling.
  • Anomalous Expansion of Stainless Steel Foil for Metal Honeycomb Catalytic Converter Induced by High-Temperature Oxidation

    pp. 851-856

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    High-temperature oxidation behavior of γ-Al2O3 slurry coated Fe-20Cr-5Al based thin foil (50μm in thickness) for a catalytic converter has been investigated. An anomalous foil expansion during high-temperature oxidation was observed in a case that the γ-Al2O3 slurry contains Ce3+ or La3+ or Y3+. The expansion was accelerated by minor additives to the stainless steel foil such as Nb, Ti, Ta, or Mo. On the other hand, the expansion was effectively suppressed by a small addition of rare-earth elements or yttrium to the stainless steel foil. It has been concluded that the foil expansion was resulted from a creep deformation by a compressive stress which is accumulated in the course of lateral growth of α-Al2O3 scale formed between the foil and the coated layer.
  • The Mechanism of The End Grain Corrosion of Stainless Steel in Nitric Acid Solutions and Its Prevention

    pp. 857-861

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    Austenitic stainless steels with low carbon content have good corrosion resistance in nitric acid solutions. However, these steels are susceptible to corrosion in nitric acid solutions which contain highly oxidizing ions such as Cr2O72-, Run+ etc. One of these is called "End Grain Corrosion" or "Tunnelling Corrosion".
    In this type of corrosion, a part of the cross-section of plate is preferentially attacked severely. In this study, it was clarified that the end grain corrosion was caused by intergranular corrosion (IGC) at phosphorus segregated areas which were induced during casting. And it was also found that the decrease of P content less than 0.015%, and heat treatments to reduce segregation of P were very effective to prevent the end grain corrosion.
  • Significance of Imaginary Initial Strain Rate and Strain Rate Acceleration Factor in a Constant Load Creep

    pp. 862-867

    Bookmark

    You can use this feature after you logged into the site.
    Please click the button below.

    Log in / Sign Up
    It has been recognized that the logarithm of creep rate varies linearly with true strain in a constant load creep. This empirical law is valid over a wide range of strain and is expressed by a following equation; ln ε=ln εo+Sε, where, ε is the strain rate, εo is the imaginary initial strain rate, S is the strain rate acceleration factor and ε is the true strain. This equation has a potential as a powerful tool for creep life and remaining life assessment technology. In the present paper, the physical significance of the two parameters, i. e., εo and S, and their stress and temperature dependences were examined by a simple thought experiment and dislocation models. It was made clear that the imaginary initial creep rate is identical principally with a steady-state creep rate and the stress dependence of S is determined mainly by the work-hardening during creep.

Article Access Ranking

27 Mar. (Last 30 Days)

  1. Dependence of Carbon Concentration and Alloying Elements on the Stability of Iron Carbides ISIJ International Advance Publication
  2. Comprehensive Optimization Control Technology of Rolling Energy and Oil Consumption in Double Cold Rolling ISIJ International Advance Publication
  3. Effects of Impurities and Processing Conditions in Al–1%Mn Alloys on the Formation of Thermally Stabilized Substructures MATERIALS TRANSACTIONS Vol.59(2018), No.11
  4. Temperature Field Distribution of a Dissected Blast Furnace ISIJ International Advance Publication
  5. Experiments on Removal of Hydrophilic Fine Particles in Bubbly Flow ISIJ International Vol.59(2019), No.2
  6. Effect of EAF Slag Temperature and Composition on its Electrical Conductivity ISIJ International Vol.59(2019), No.2
  7. Coating Film Profiles Generated by Fluctuating Location of the Wiping Pressure and Shear Stress ISIJ International Vol.59(2019), No.2
  8. Structure Based Viscosity Model for Aluminosilicate Slag ISIJ International Advance Publication
  9. Numerical Simulation of Multiphase Flow and Mixing Behavior in an Industrial Single Snorkel Refining Furnace (SSRF): The Effect of Gas Injection Position and Snorkel Diameter ISIJ International Advance Publication
  10. Change in Composition of Inclusions through the Reaction between Al-killed Steel and the Slag of CaO and MgO Saturation ISIJ International Vol.59(2019), No.2

Search Phrase Ranking

27 Mar. (Last 30 Days)

  1. blast furnace
  2. blast furnace permeability
  3. blast furnace productivity
  4. galvanizing
  5. tuyere abrasion
  6. tuyere erosion
  7. tuyere failure
  8. lme
  9. wear on tuyere
  10. 鉄と鋼