Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 56 , Issue 13
Showing 1-21 articles out of 21 articles from the selected issue
  • Bunsho HIRAOKA
    1970 Volume 56 Issue 13 Pages 1575-1582
    Published: November 01, 1970
    Released: October 12, 2010
    Lots of simulation have been applied to the iron and steel making processes and especially fluid flowmodels are helpful in investigating the gas flow in the furnace.
    The reconstruction of the three zone pusher furnace was planned to increase its heating capacity.Enlargement of the combustion space was aimed by raising the furnace roof and this also made itnecessary to pursuit the most suitable position and direction of burners in each zone. In addition, theroof height at the nose of soaking zone and the preheating zone was discussed and the effect of pilingup of scale on the gas flow was also considered. Then gas flow patterns in the furnace wereexamined under these various conditions. These tests resulted in the most desirable design of the furnacein its line and burner setting. The furnace was reconstructed satisfactorily according to these results.
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  • Hiroo KOBAYASHI, Takeji OYAMA, Takeo Ao
    1970 Volume 56 Issue 13 Pages 1583-1593
    Published: November 01, 1970
    Released: October 12, 2010
    Twenty-eight kinds of oxides, in amounts up to five weight per cent, were added into zircon in orderto investigate their effects on decrement of apparent porosity and dissociation of zircon refractoriesduring sintering at 1 500°C
    Na2O, K2O, MgO, CaO, ZnO, B2O3, MnO2, Fe2O3, Co2O3, and NiO promoted markedly sinteringof zircon. Cu2O, CuO, BeO, CeO2, TiO2, P2O5, SrO, and BaO did slightly, but ThO2, Al2O3, SnO, Pb2O, PbO, V2O5, SeO2, Cr2O3, MoO3 and WO3 did not.
    Among the oxides that promoted sintering of zircon, Cu2O, CuO, BeO, CeO2, TiO2, P2O5 Fe2O3, NiO, ZnO MnO2 and Co2O3 had almost no effect on the dissociation of zircon at 1500°C.
    When specimens contained these oxides were kept for two hours at 1600°C. The dissociation of zirconwas not affected by addition of BeO, ZnO, Fe2O3 nor NiO, whereas it was affected a little byaddition of Cu2O or CO2O3, and markedly by addition of TiO2.
    The result of slagging test for specimens containing Fe2O3, ZnO, or Co2O3 was satisfied but that forCu2O, or NiO was unsatisfied.
    Conclusively, zircon refractories containing a little amount of Fe2O3, ZnO, or Co2O3 had lowerapparent porosity without little dissociation of zircon at 1500°C and had better result for slagging test.
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  • Hideo SHIMAMURA, Toshikatsu TERUI, Yasuo OMORI, Koji SANBONGI
    1970 Volume 56 Issue 13 Pages 1594-1601
    Published: November 01, 1970
    Released: October 12, 2010
    Reductions of iron-oxide pellets in fixed bed and single pellet with CO gas were fundamentally studiedin order to determine the reducibilities of pellets. The results are summarized as follows.
    On the reduction of pellets in fixed bed with CO gas:
    1) Since distribution of gas concentration changed in axial direction, reduction degree of pelletbecame different between the upper and lower layer in fixed bed. As a result, critical value of gasflow was not obtained.
    2) Size of pellet affected largely its reducibility, then the size of sample should be selected to benarrow range of ± mm.
    3) Both the equation of 1st order reaction proppsed by German researchers and other equations sometimeswere satisfied with the experimental values, but they must be studied in more datail to beused as the method for indicating the reducibility of pellet.
    From the present experimental results, it can be concluded that method for reduction of single: pellet isto that in fixed bed because the parameters (for example, k or D) obtained from its test are able to apply the process analysis.
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  • Kiichi NARITA, Akitsu TOMITA, Yasuo HIROOKA, Yoshitomo SATOH
    1970 Volume 56 Issue 13 Pages 1602-1612
    Published: November 01, 1970
    Released: October 12, 2010
    A study has been made of cold model experiments and hot model experiments on the desulphurizationof molten pig iron by means of injecting calcium carbide.The results reported here are summarized as follows:
    1) By the cold model experiments, effects of stirring solution in a ladle model is significant whena lance is immersed more than half of the bath depth. In this case the stirring effect is not affectedby the immersion position of the lance in a ladle model, either center or wall-side.
    2) A hot model experiments based on the cold one indicated that both results for desulphurizationeffects coincided very well, for example, effects of the immersion depth of lance could be applied toeffects of desulphurization of molten pig iron.
    3) Injection method, when a lance is immersed more than half of the bath depth, has a high degreeof utilization of calcium carbide and a large effect of desulphurization per weight of molten pig iron.
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  • Zen-ichiro MORITA, Yoshikiyo OGINO, Takeshi IBA, Tadao MAEHANA, Akira ...
    1970 Volume 56 Issue 13 Pages 1613-1632
    Published: November 01, 1970
    Released: October 12, 2010
    Knowledge of viscosity of liquid metals and alloys is valuable pratically and theoretically, and accuratedata should be particularly important on the consideration of the structure of liquid metals andalloys. An accurate measurement of viscosity, however, especially on high temperature such as on liquidiron is quite difficult and most of the data having been obtained may be dcubtful in their reliability.For the purpose of carrying out precise measurement of viscosity of liquid metals and alloys at hightemperature an improved apparatus for viscosity measurement by oscillating crucible method wasmade, and through the experiments using this apparatus some fundamental problems on the viscositymeasurement were analytically examined and discussed.The main results obtained are summarized as follows:
    (1) From an analysis of the oscillation modes on distilled water, n-heptane and liquid mercury, itwas concluded that oscillation periods shorter than about 4 seconds should not be employed for themeasurement because of the occurrence of the irregular flow in liquid. The most reliable result wasobtained at the periods of about 7 seconds on present apparatus.
    (2) The atmosphere used in the viscosity measurement is very important factor affecting theaccuracy of the measurement especially at high temperature. Although Ar was inadequate forthis purpose on account of its large disturbing effects on the oscillation, in He atmosphere these effectswere remarkably small. Therefore, the use of He was considered to be preferable.
    (3) From a series of experimental analysis, it was confirmed that under the suitable experimentalcondition it was possible to measure the viscosity of liquid metals and alloys at high temperature with sufficient accuracy using the apparatus presented in this paper.
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  • Yoshikiyo OGINO, Zen-ichiro MORITA, Tadao MAEHANA, Katsuhiro YOKOTANI, ...
    1970 Volume 56 Issue 13 Pages 1633-1639
    Published: November 01, 1970
    Released: October 12, 2010
    It is well-known that viscosity is quite important as a “structure sensitive” property to investigate the structure of liquid metals and alloys. For the curpcse of obtaining some knowledges on the structure of liquid iron and nickel, viscosity was precisely measured on these metals in the temperatures between 1490 and 1700° and 1466 and 1665° respectively, by means of oscillating crucible method.
    From the results of this measurement, it was found that the viscosity coefficient of liquid iron discontinuosly changed in the temperature range between 1580 and 1640°, and activation energies for viscous flow were 11·0 and 6·9 kcal/ mol at the temperaturesab ove 1640° and below 1580°, respectively. These facts indicate that certain structural change occurs in liquid iron at the temperatures corresponding to the discontinuous change of viscosity. This structural change may be well explained to be the break down of bcc-like short range order presumably existing at the lower temperatures and subsequent increase of randomness of atomic distribution. On the other hand, such a structural change in liquid nickel was not recognized in the range of experimental temperature between 1466 and 1665°.
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  • Teinosuke YAGI, Yoichi ONO, Makoto USHIJIMA
    1970 Volume 56 Issue 13 Pages 1640-1645
    Published: November 01, 1970
    Released: October 12, 2010
    Diffusion coefficients of chromium, manganese and nickel in molten iron saturated with carbon were measured by a capillary reservoir method in the temperature range of 1 350° to 1 550°.
    The results were summarized by the following ARRHENIUS' equations:
    The values of diffusion coefficient increased in the zrder, Cr, Mn, Ni, and both the values of activation energy and frequency factor increased in the order, Cr, Ni, Mn.
    It was confirmed by the measurements of concentration distribution in the capillary samples that all the boundary conditions for the capillary reservoir method were satisfied and that the diffusion occurred under the condition of carbon saturation.
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  • Nobuya IWAMOTO, Hideo YOSHIDA, Akira ADACHI
    1970 Volume 56 Issue 13 Pages 1646-1660
    Published: November 01, 1970
    Released: October 12, 2010
    Deoxidation products in Fe-Ti alloys were investigated. It was determined that inclusions formed varied their structure to liquid oxide (it's structure is spinel 2FeO.TiO2 or ilmenite FeO·TiO2), solid solution of Ti3O5 and FeO·2TiO2 and Ti2O3 with an increase of the amounts of titanium added.
    Isothermal phase diagram of Fe-Ti-O ternary system at 1500° was established and the following results were obtained.
    1) Pseudobrookite and anasovite can form pseudobinary system and they are able to dissolve completely each other.
    2) Ti2O3 is able to equilibrate with the metallic phase containing titanium up to 27% and this fact agrees with the result of deoxidation products.
    As for deoxidation products of vanadium, it was verified that they appear as spinel FeO, V2O3, V203 and VO with an increase of the amounts of vanadium added. Moreover, FeO - V2O3 changes an amounts of wustite dissolved owing to oxygen partial pressure equilibrated.
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  • Nobuya IWAMOTO, Akira ADACHI
    1970 Volume 56 Issue 13 Pages 1661-1676
    Published: November 01, 1970
    Released: October 12, 2010
    It is necessary to analyse the fomation behaviour of tetragonal chromite from the crystallographical and technological viewpoints.
    Various physical means such as high temperature X-ray, Massbauer resonance and X-ray emission peak shift studies have been employed in this investigation.
    Results obtained were as follows:
    1) Mössebauer resonanse study indicate that all the tetragonal chromites have quadrupole splitting. The value becomes larger as the tetragonality of chromite increases. This tendency agrees with the Crka doublet shift study. It is also found that the existence of Cr2+, may disturb the cubic symmetry in the chromite crystal field.
    2) From the high temperature X-ray diffraction study, it was found that the experiment at lower temperature such as 100-200°C should be performed precisely to pursue whether Jahn-Teller effect contributes to tetragonal chromite.
    3) Chromium content in the inclusions extracted from the high-chromium alloys is over the stoichiometric composition of FeCr2O3. This fact agrees with the results obtained from the synthesis of the tetragonal chromite.
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  • Mamoru MIWA, Shigeo ASAI, Iwao MUCHI
    1970 Volume 56 Issue 13 Pages 1677-1686
    Published: November 01, 1970
    Released: October 12, 2010
    Mathematical model for determining the variations of process variables which take place with the progress of blowing in LD converter is developed in this work.
    Concerning the oxidations of phosphorus and manganese, direct oxidations by oxygen gas occurring at cavity and indirect oxidation by wustite taking place at the interface between slag and metal have been taken into account in the model. Furthermore, a modified phase diagram for the ternary system (CaO)-(FeO)-(SiO2) has been applied to modeling the process of lime solution.
    On the basis of the model, numerical calculations have been conducted under various operating conditions with the aid of digital computer. The results calculated on the variations of process variables have been compared with the experimental data obtained by other investigators and the former has been in good agreement with the latter.
    The effects of the mass of lime solved in the bath, of the slag basicity and of the bath temperature on the fractional dephosphorization at the end of blowing have been evaluated by use of the model under the hypothetical operating conditions and the maximum value of fractional dephosphorization has been illustrated theoretically in this paper.
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  • Akinori MISAWA, Iwao MUCHI
    1970 Volume 56 Issue 13 Pages 1687-1698
    Published: November 01, 1970
    Released: October 12, 2010
    In order to get useful informations for improving operating conditions in DH degassing process, a mathematical model is developed in this work.
    In this model, the suction period when molten steel flows up into vacuum vessel from ladle and the discharge period when molten steel flows down into ladle from vacuum vessel have been analysed theoretically, and variations of gas pressure in vacuum vessel during degassing process have been considered.
    On the basis of the model, the effects of the operating variables, namely, volume flow rate of exhaust gas, suction rate of molten steel and suction ratio of the volume of molten steel in vacuum vessel to the total volume of molten steel, on the degassing rate have been calculated with thd aid of digital computer.
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  • Hiroshi NAGAYAMA
    1970 Volume 56 Issue 13 Pages 1699-1715
    Published: November 01, 1970
    Released: October 12, 2010
    In order to know the source of macroscopical inclusions by mineralo-chemical method, mineralogical composition and microscopical structures of exogenous source substance in steelmaking process of bottomand top teeming ingot were investigated in connection with those of ingot scums.
    The following conclusions were obtained.
    (1) The values of CaO/SiO2, CaO/Al2O3 and (Fe, Mn) O/SiO2 of exogenous source substance fell gradually with progress of casting process, and the values of constituent minerals of ingot scums were equal to those of altered refractories at the end of casting process.
    (2) The chemical and mineralogical composition of ingot scums was similar to that of altered refractories at the end of casting process, and it was considered that mixing of these altered refractories played an important part in forming ingot scums.
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  • Hiroshi NAGAYAMA
    1970 Volume 56 Issue 13 Pages 1716-1725
    Published: November 01, 1970
    Released: October 12, 2010
    In order to investigate the source of slag inclusions, zircon sand (ZrO2·SiO2) was added in the reducing slag of 10 t electric furnace and calcium zirconate (CaO·ZrO2) was produced.
    The behavior of slag inclusions studied by determining ZrO2 content in oxide inclusions extracted from steel specimens.
    The results are as follows.
    1) Slag inclusions were mainly originated from the tapping slag in electric furnace process, and a small part of them was originated from the altered layers of ladle bricks.
    2) On the basis of some experiments, it was considered that fine slag grains mixed into molten steel as calcium zirconate reacted with α-Al2O3 that was producd by Al deoxidation in the ladle, and ZrO2was dissociated from the calcium zirconate. Consequently, baddeleyite (ZrO2) was found in slag inclusions.
    3) Some considerations on zircon tracer method for investigating the source of slag inclusions were discussed comparatively with RI tracer method.
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  • Tadashi ICHIYAMA, Ikushi YOSHIDA, Yasuhiro NAKAGAWA, Mizuo EJIMA, Osam ...
    1970 Volume 56 Issue 13 Pages 1726-1736
    Published: November 01, 1970
    Released: October 12, 2010
    Recovery, recrystallization, and texture-development in cold-rolled sheets of an Fe-Al-N alloy with 0.061% of acid soluble aluminum and 0.0047% of acid soluble nitrogen were studied. Two different initial conditions as for the AIN precipitation were given by quenching the hot-rolled strip into brine water either directly from the hot-finishing temperature or after keeping it at 800°C for 30 minutes so that AIN precipitated completely.
    Highly developed {111} recrystallization texture was found in the specimen with nitrogen and aluminum initially in solution, while in the course of heating a noticeable retardation of strain recovery occurred. An analysis of X-ray diffraction line broadening showed that the retardation of strain recovery was anisotropic, being most pronounced for grains with the {111} lattice plane parallel to the sheet plane. Such effect was not found in the specimen with AIN precipitated prior to cold-rolling. Comparing the above result with that of transmission electron microscopy, a discussion was made concerning the differences in the annealing behavior and the texture-development.
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  • Toru ARAKI, Ryuhei SAGAWA, Tzu-Ye SHIH
    1970 Volume 56 Issue 13 Pages 1737-1746
    Published: November 01, 1970
    Released: October 12, 2010
    Fatigue tests have been carried out with vacuum degassed (DH-treated) and not-DH-treated martensitic steels by repeated bending with tension side amplitude.
    It was found that fatigue microcracks nucleated on the edge of specimen in the DH-treated steel, but from non-metallic inclusion in the not-D H-treated steel. It was also found that microcracks nucleated from inclusions were of 3 types; initiated by the fracture of inclusions themselves, by the separation at the inner boundary of duplicated inclusions, and also by the separation at the interface with matrix. From the observation of surfaces and microfractographs, a fatigue crack propagation mechanism is suggested as follows. The inclusions are considered to nucleate sub-cracks that grow into shear mode fracture, at high plastic zone in front of the main crack tip. As the main crack approaches, they join and link by cleavage or quasi-cleavage fracture wi th the main crack. This process is repeated to make the crack propagate.
    An attempt has been made to represent the rate of crack propagation by the following relationship:
    where l is length of the main crack and B is considered as a function of stress and material.
    It was evident that the vacuum degassed clean material was excellent compared with the ordinary meterial in view of fatigue crack nucleation and propagation.
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  • Muneyoshi TAKEYAMA, Masayoshi HASEGAWA, Masafumi OKAMOTO, Kazunori TOK ...
    1970 Volume 56 Issue 13 Pages 1747-1756
    Published: November 01, 1970
    Released: October 12, 2010
    Fe2W, Fe2Nb and Fe2Ta Laves phases (MgZn2 type C 14) were found in iron alloys containing 6.95 wt % W, wt % Nb and 0.86-2.40 wt % Ta. The activation energy for the formation of this phase was estimated at about 51.0 kcal/mol in the Fe-W, 61.5-64.3 kcal/mol in the Fe-Nb and 60.0-60.4 kcal/mol in the Fe-Ta binary alloy by hardness measurements. An addition of niobium or tantalum to pure iron was effective for solution and precipitation hardening, and both elements showed the similar effects as solute at once. In the ternary alloys containing nickel, manganese, cobalt, silicon and chromium, the precipitation process of Laves phase was similar to that in the binary alloy, on the other hand, in the Fe-W-Mn ternary alloy containing 5.6 wt % manganese the reversed austenite precipitated in Widmanstatten wise in the ferritic matrix at aging temperature 650-850°, and this austenite transformed to martensite by water-quenching from aging temperature.
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  • Katao MIYANO, Takao ADACHI
    1970 Volume 56 Issue 13 Pages 1757-1765
    Published: November 01, 1970
    Released: October 12, 2010
    21/4Cr-1 Mo steel are generally used for the huge reactor vessels that operate at high pressure andelevated temperature, because of its good short and long time elevated tensile properties and its goodresistance to hydrogen attack. Requirements for higher operating volume and pressure have accelerateda demand for reactor vessels of extra heavy gauge wall thickness and upgraded mechanical properties throughout the thickness.
    To obtain informations needed for effetive uses of 21/4Cr-1 Mo steels, a fundamental and systematicstudy was carried out on the heavy gauge steels of 100-400 mm in thickness. In this study, the effectof cooling rates from austenitizing temperature on microstructures, the effect of cooling rates andtempering cycles on mechanical properties and elevated temperature tensile properties were investigated.
    The results obtained are as follows:
    (1) Uniform bainitic structure is obtained when the cooling rate is faster than 6°C/min, and theblockish ferrite increases with decrease rate, which deteriorates mechanical properties.
    (2) The effect of various heat treatment cycles on room temperature tensile properties is shownas a function of LARSON-MILLER'S tempering parameter, and 21/4Cr-1 Mo steels in the ultimate tensilestrength range from 56kg/mm2 to 90 kg/mm2 can be manufactured by the suitable tempering cycles.
    (3) To maintain excellent notch toughness, the cooling rate faster than 6°C/ min is desirableand in the special case of manufacturing high tensile steels which are tempered at low temperature (UTS is over than 70kg/mm2), 10-15°C/min or faster cooling rate is recommendable.
    (4) By applying the results mentioned above, 365 mm thickness forged shell was cooled in agitatingwater and the excellent mechanical properties and satisfactory bainitic structure was obtainedthroughout the thickness.
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  • Toshiji SHIMIZU, Ichiro TAKAHASHI, Yohachi HIRATA, Takeshi YOSHIDA
    1970 Volume 56 Issue 13 Pages 1766-1774
    Published: November 01, 1970
    Released: October 12, 2010
    Cu bearing 18-8 stainless steels are well known to be liable to cracks by hot working. In order to investigate the effects of chemical composition and metal structure on the hot cracking, hot upsettingtests were carried out.
    The results are summarized as follows.
    (1) Many cracks were found above 4% of copper content, but a few cracks, below 4%.
    (2) In the case of 2% of copper content, cracks tended to decrease with the decrease of chromiumcontent and the increase of nikel content.
    (3) Cracks propagated mainly along δ-ferrite, and cracking tendencies were estimated by Nibalanceand the amount of 5-ferrite in the as-cast state.
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  • Rikizo WATANABE, Tsuneo KUNO
    1970 Volume 56 Issue 13 Pages 1775-1780
    Published: November 01, 1970
    Released: October 12, 2010
    Effects of the intermediate aging condition on the cellular precipitation of 72 phase at grain boundary and mechanical properties of an iron base super alloy, V 57 have been investigated and the relation ship between the amount of η phase and mechanical properties has been discussed.
    η phase increases with the increase of intermediate aging temperature and time, and decreases withraising preheating temperature before the intermediate aging because of γ′ precipitation during preheating.
    Grain boundary η phase has little effect on tensile strength at room temperature. The increase ofgrain boundary η phase causes slight decrease of tensile elongation at room temperature, remarkabledecrease of stress rupture life and also remarkable increase of stress rupture elongation.
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  • Jiro SATAKE, Taishi MOROISHI
    1970 Volume 56 Issue 13 Pages 1781-1785
    Published: November 01, 1970
    Released: October 12, 2010
    Water permeability of rust layers formed on a carbon steel and a low alloy steel by at mospheric corrosionwas evaluated by means of impedance measurement of the rusted specimen electrode in 0.1 Msodium benzoate aqueus solution. Resistance of rust layer decreases with immersion time as the solution penetrates into the rust and finally attains a steady state. Initial and final values of the resistanceand also the time necessary to reach the steady state increase with increasing of the periods of atmosphericex posure. These values are larger for low alloy steels than those for the carbon steel at the sameexposure time. The linear relationship has been confirmed between atmospheric corrosion rates and reciprocals of the final resistances which provide a sort of measure for the porosity of rust layer. Incase of low alloy steel the deviation of the final values from the linearity is found and the initialvalues come to agree with the line as exposure time becomes longer. It is supposed that corrosionrate depends on the time of wetness which determines how large is the area on the steel surfacewhere the water reaches through the porosities and corrosion starts.
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  • 1970 Volume 56 Issue 13 Pages N185
    Published: 1970
    Released: October 12, 2010
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