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 Advance Publication

  • Behavior of Crystallization on a Continuous Solidification Process of Blast Furnace Slag

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-032

    A continuous blast furnace slag solidification process was developed to promote the use of air-cooled slag coarse aggregate for concrete. In this process, molten slag can be solidified in only 120 seconds, and the thickness of the slag is about 25 mm. After crushing the slag, the water absorption ratio is much lower than that achieved in the past because gas generation is suppressed. With this apparatus, most of the slag is crystalline, but part of the slag has a glassy surface. Therefore, EPMA and XRD were used to study the glass transition phenomenon. It found that the thickness of the glass layer is about 2 mm. To discuss the glass transition and crystallization phenomena, the thermal history was simulated by heat transfer analysis. The results clarified the fact that all the slag on the mold has a glassy surface layer of about 2 mm, and good agreement between the calculation and experimental data concerning the layer was obtained. It was also shown that most of the slag crystallizes in the slag pit because the temperature inside the piled slags rises to more than 1173 K. The measured slag temperature and calculated temperature were also in good agreement.
  • Observation of Chemical State for Interstitial Solid Solution of Carbon in Low-carbon Steel by Soft X-ray Absorption Spectroscopy

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-050

    Observation of chemical state of solid-solution carbon in a low-carbon steel was tried by C-K near-edge x-ray absorption fine structure spectra measurement. In addition, the wavelength dependence of the photoelectron spectrum on the surface of the bulk steel was evaluated, and the contamination and oxidation layer of 3 nm in thickness on the surface of the steel was found. As a result, it was possible to observe the chemical state change of carbon existing in the bulk iron located deeper than the oxidation and contamination layer, by evaluating the difference spectra between the sample and the reference. Furthermore, by evaluating the shape change of the difference spectra depending on the heat treatment time, this study suggested that the chemical state of carbon in bulk iron changes with heat treatment.
  • Lattice Strain and Strength Evaluation on V Microalloyed Pearlite Steel

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-041

    Strengthening effect by microalloyed vanadium (V) on eutectoid pearlite steel has been investigated from the perspective of nano-precipitation and lattice strain. 0.2% proof stress of specimens, isothermally transformed at 873 K, increases around 160-170 MPa with 0.1% V addition. However, interphase precipitation of vanadium carbide (VC), regarded as the principal strengthening factor, has not been detected by transmission electron microscopy or 3D atom probe microscopy (3D-AP). On the other hand, lattice strain in lamellar ferrite, analyzed by broadening of X-ray diffraction peak, has clear correlation with proof stress. The lattice strain data of 0.1% V added pearlite specimens are plotted on the same correlation line as of V free ones. In addition, elemental map by 3D-AP shows that vanadium atoms concentrate in lamellar cementite rather than ferrite, which could change cementite lattice parameters and gain ferrite/cementite misfit causing lattice strain increment. These results reveal that microalloyed V influences not only precipitation of VC in lamellar ferrite, but also the lattice strain increment in pearlite lamellar. As far as pearlite steels containing at most 0.1% V, lattice strain is considered to be the major factor of their yield behaviors. Furthermore, 0.1% V addition has not enhanced work-hardening behavior as notably as estimated by Ashby’s work-hardening theory of dispersion-hardened crystals. Therefore, VC precipitation should not necessary for V strengthening effect on pearlite steel.
  • Recovery of Neodymium from Neodymium Magnet Using Bismuth

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-037

    Experiments were conducted to extract neodymium in bismuth by melting Fe-Nd-B magnets and bismuth together in a graphite crucible at 1200°C. Molten iron and bismuth separated into two phases, and neodymium in the magnet dissolved in the bismuth phase. Neodymium dissolved in bismuth was considered to form BiNd as a result of XRD. The neodymium concentration in iron phase after the dissolution treatment was 0.05 at.% or less,and the recovery rate was 99% and more. Compared to other metals(Mg, Ag, Cu) that separate into two phases with respect to molten iron, bismuth can be said to be a metal extraction material with a low melting point, safety and low energy cost.
  • Simulation of Snaking and Buckling in Hot Sheet Rolling

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-023

    In hot sheet rolling, the sheet end often snakes, contacts the side guide, buckles, and goes into the roll gap, while the overlapped sheet end is squeezed. Although many simulations on sheet snaking are reported, very few researches have been performed to simulate both the sheet snaking and sheet buckling. In this study, we proposed a combined method to simultaneously simulate the sheet snaking through the rigid-plastic FEM and to analyze the sheet buckling by the elementary theory of buckling. The in-plane lateral load and the in-plane bending moment were assumed at the surface of the region for the simulation by the rigid-plastic FEM. The amount of snaking at the sheet end simulated by the rigid-plastic FEM agreed with that calculated from the analysis by the elementary theory. Finally, we clarified the effects of rolling conditions on the occurrence of squeezing, such as the difference in the sheet thickness in the roll axis direction, the difference in the roll gap in the roll axis direction, and the amount of the off-center.
  • Effect of Crystal Structure of Surface Compound Layer on Fatigue Strength of Nitrided SCM 435 Steel

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-011

    Effect of crystal structure of surface compound layer on the fatigue strength of nitrided SCM 435 steel was investigated. Specimens in which the crystal structure of the surface compound layer was controlled to γ’-Fe4N phase or ε-Fe2-3N phase were prepared by gas nitriding treatment capable of changing nitriding potential (KN). Axial fatigue test were conducted to the specimens. Even in each test specimen which has different crystal structure of the compound layer, distribution of residual stress and hardness in the nitrogen diffusion layer exhibited almost same values. It is revealed that fatigue strength significantly depends on crystal structure of surface compound layer. Specimens with γ’-Fe4N phase dominant shows substantially high fatigue strength comparing to specimens with ε-Fe2-3N phase dominant. In the fatigue test under stress ratio R=0, the specimen from which the surface compound layer was removed showed the highest strength. The fatigue strength is considered to be governed by the fracture strength of each compound layer. Namely, in the specimen with ε-Fe2-3N phase dominant, fatigue cracks are induced by fracture of brittle ε-Fe2-3N phase layer and progress into nitrogen diffusion layer due to stress intensity factor (ΔK) at crack tip exceeds the threshold of stress intensity factor range (ΔKth) in the matrix. On the other hand, in the case of γ’-Fe4N phase dominant, γ’-Fe4N phase with high toughness showed high fatigue strength due to suppress the crack initiation up to a higher stress level.
  • Improvement of Surface Roughening Resistance of Ultra-Low-Carbon Steel Sheet by Reducing {001} Oriented Crystal Grains

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-033

    Because of the increasing demand for automobile outer panels with sharper streamlines, it is important to improve the surface qualities of outer panel products. In the present study, the effects of microstructural properties – particularly the deformation-mode dependence of heterogeneous deformation at the grain scale and the fraction of {001} oriented grains – on surface roughening during deformation were investigated experimentally. The results showed that surface roughening decreased as the average grain size and the fraction of {001} oriented grains decreased. These trends were more pronounced under equibiaxial tension than under plane-strain tension. Surface roughening decreased with the fraction of {001} oriented grains, presumably because the heterogeneity of deformation resistance decreased at the grain scale. Moreover, if the texture and average grain size were similar, the development of surface roughening in the low-strain range (equivalent plastic strain of less than 0.3) was independent of the work-hardening coefficient n. On the basis of the abovementioned results, the optimum annealing conditions were examined to realize crystal grain refinement and reduction of {001} orientation. As a result, we obtained a high-strength steel with excellent surface roughening resistance.
  • Identifying Factors for Cu Contained in Carbon Steel Produced in Japan

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2018-009

    The steel industry has been concerned with contamination by tramp elements during repeated recycling of carbon steel. Increase of Cu content has never been observed at least by monitoring EAF steel bars from the late 1980s. However, the increase may happen in future. To surely avoid the increase which leads to ineffective recycling, mechanisms of Cu mixing in carbon steel should be understood. The factors for Cu in carbon steel produced in Japan were identified. We distinguished two sources of Cu in obsolete steel scrap: Cu alloyed in carbon steel which has been contaminated by previous recycling and Cu contained in materials beside carbon steel. We found that, by dynamic material flow analysis, the Cu content derived from the former source has gradually increased because of increasing shares of bar and section which have a relatively high Cu content, which leaded to 0.05% increase in Cu content during three decades. On the other hand, Cu derived from the latter has become smaller from the late 1990s. One of the reasons was thought as increase of exporting scrap-mixed metal (often termed “zappin scrap”) from around the year. In the near future, it is predicted that the substantial part of the export will be rapidly reduced by amendment of relevant regulations. We estimate that Cu content in steel bars will become 0.49% on the average, if scrap-mixed metal is domestically recycled in a commercial way. This result underlines the necessity of improving the separation of Cu materials from carbon steel scrap.
  • Causes of Pinhole Generation on Solidification of Low Carbon S-Pb Free-cutting Steel Cast Continuously

    Bookmark

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

    Log in / Sign Up

    DOI:10.2355/tetsutohagane.TETSU-2017-098

    In this study, in order to prevent occurrence of surface cracks caused by pinholes occurring in production of low-carbon S-Pb free-cutting steel using continuous casting, on the causes of pinholes generation in this steel, the generating behavior of bubbles in front of solid/liquid interface and engulfment behavior of bubbles by solidifying shell has been theoretically examined from the viewpoint of transport phenomena, thermodynamics, and interfacial science, and the cause of pinhole generation on solidification has been clarified.Since the oxygen concentration of molten steel is high for undeoxidization to ensure machinability, the CO partial pressure at solid/liquid interface is significantly high due to solute enrichment on solidification. And additionally it is presumed that bubbles tend to be generated at the interface because the total gas pressure increases due to evaporation of lead. Furthermore, it was estimated that this steels are extremely high in sulfur concentration, and the surface tension at solid/liquid interface greatly decreases due to the enrichment at the interface, which also promotes the generation of bubbles on solidification. The CO partial pressure of the total gas pressure accounted for about 90%, and it was estimated that decreasing the CO partial pressure is most important in suppressing bubble generation by proper control of carbon and oxygen content of molten steel and application of stirring of molten steel.Furthermore, it has been clarified that detachment of the bubbles from the solid/liquid interface is suppressed by the interfacial tension gradient caused by the concentration gradient of sulfur and/or oxygen.

Article Access Ranking

20 Jul. (Last 30 Days)

  1. Production and Technology of Iron and Steel in Japan during 2017 ISIJ International Vol.58(2018), No.6
  2. Bend Failure Mechanism of Zinc Coated Advanced High Strength Steel ISIJ International Advance Publication
  3. Effect of Annealing Temperature on the Selective Oxidation and Reactive Wetting of a 0.1C-6Mn-2Si Advanced High Strength Steel During Continuous Galvanizing Heat Treatments ISIJ International Advance Publication
  4. An Analysis on Global Energy-Related CO2 Emission Reduction and Energy Systems by Current Climate and Energy Policies and the Nationally Determined Contributions Journal of the Japan Institute of Energy Vol.97(2018), No.6
  5. Effect of Si Content on the Microstructure and Wear Resistance of High Chromium Cast Iron ISIJ International Advance Publication
  6. In Situ Temperature Measurement of Sinter Beds at High Spatial and Time Resolution ISIJ International Vol.58(2018), No.5
  7. Effect of MgO on Formation and Crystallization Behaviors of Calcium Ferrite during Heating and Cooling Processes ISIJ International Advance Publication
  8. CO2 Reduction Potential of Solar Water Heating Systems on a Municipal Basis Journal of the Japan Institute of Energy Vol.97(2018), No.6
  9. Granulation Effectiveness of Iron Ore Sinter Feeds: Effect of Ore Properties ISIJ International Advance Publication
  10. Influence of Deformability of Retained Austenite on Martensitic Transformation in Tension for Low Alloy Steel at Low Temperatures ISIJ International Vol.58(2018), No.6

Search Phrase Ranking

20 Jul. (Last 30 Days)

  1. blast furnace
  2. steel
  3. blast furnace productivity
  4. blast furnace permeability
  5. 鉄と鋼
  6. cral
  7. dem
  8. electric arc furnace
  9. heat balance
  10. hot stamping