Tetsu-to-Hagane
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
Volume 67 , Issue 14
Showing 1-22 articles out of 22 articles from the selected issue
  • Tadashi OHTAKE
    1981 Volume 67 Issue 14 Pages 2073-2085
    Published: 1981
    Released: June 19, 2009
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  • Taiji NISHIZAWA, Mitsuhiro HASEBE
    1981 Volume 67 Issue 14 Pages 2086-2097
    Published: 1981
    Released: June 19, 2009
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  • Ken'ichi SHIMIZU
    1981 Volume 67 Issue 14 Pages 2098-2107
    Published: 1981
    Released: June 19, 2009
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  • Hirofumi YOSHIMURA
    1981 Volume 67 Issue 14 Pages 2108-2116
    Published: 1981
    Released: June 19, 2009
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  • Yasushi UENO, Shunichi SUGIYAMA, Kazuo KUNIOKA
    1981 Volume 67 Issue 14 Pages 2117-2124
    Published: 1981
    Released: June 19, 2009
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  • Takashi CHIHARA
    1981 Volume 67 Issue 14 Pages 2125-2130
    Published: 1981
    Released: June 19, 2009
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  • Kimihisa ITO, Nobuo SANO
    1981 Volume 67 Issue 14 Pages 2131-2137
    Published: 1981
    Released: June 19, 2009
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    The equilibrium concentrations of Ti3+ and Ti4+ in the molten CaO-SiO2-Al2O3-MgO system with TiC, C and atmospheric CO were determined in the temperature ranging from 1 400° to 1 550°C in order to clarify the mechanism of the formation of titanium carbonitride at the hearth of a blast furnace. The γTio1·5 and γTio2 values were calculatcd from the determined concentrations as well.
    The Ti4+ ion in slags is found to behave amphoterically with the critical CaO/SiO2 equal to unity. The Ti3+ ion behaves basic except in highly basic slags such as in the CaO-Al2O3 system, where it turns out to behave acidic.
    It is indicated by the thermodynamic calculation including the data of the present work that the actual blast furnace slag contains titanium abundantly enough to form Ti(CN). In view of the sluggish formation of TiC from slags and graphite, the protective titanium bear on the hearth is likely to form on the reaction in which hot metals take nart.
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  • Yasushi NAKAMURA, Kazumi HARASHIMA, Yoshimori FUKUDA
    1981 Volume 67 Issue 14 Pages 2138-2144
    Published: 1981
    Released: June 19, 2009
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    Liquid 4% C-Fe alloy at 1 350°C was refined with CaO-based fluxes (CaO-SiO2-Fe2O3) containing chloride and/or fluoride compound of metals (Li, Na, K, Mg, Ca, Ba, Al and Fe), in order to study the effect of halide addition on the refining power of CaO-based flux. A rotating crucible containing 1 kg alloy was used to avoid the reaction between the molten flux and the crucible. Weight ratios of the flux to the alloy and the halide compound to CaO were 0.030-0.037 and 0.4-0.6, respectively. The refining power of Na2CO3-based flux (Na2CO3-SiO2) without an addition of halide compound was also studied in comparison with that of CaO-based fluxes.
    The experimental results showed that the addition of the halide compounds enhanced both the rate and the degree of phosphorus removal except the cases of KCl and NaCl addition. Na2CO3-based flux showed the excellent dephosphorizing power in the whole range of basicity studied. In a limited range of basicity from 4 to 6, however, CaO-based fluxes containing LiF, LiCl, CaCl2 and CaCl2-CaF2 revealed the dephosphorizing power comparable to that of Na2CO3-based flux; the degree of phosphorus removal was nearly 90%. The degree of sulfur removal attained by CaO-based fluxes (0-80%) was lower than that of Na2CO3-based flux (85% or more).
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  • Keizo YAMADA, Hiroyuki AZUMA, Takeshi HIYAMA, Kosei SUGIMURA
    1981 Volume 67 Issue 14 Pages 2145-2151
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Utilization of molten ferroalloys in making stainless steels was succeeded in the Hachinohe Works of Pacific Metals Co., LTD. (PAMCO), and LD-AOD process which is one of the P.H.A. process (PAMCO-HOT-ALLOY process) was developed.
    The trial heats proved that the LD-AOD process was able to apply to production runs with no difficulties. The characteristic features of the process are as follows;
    1) An enormous increase in chromium and tapping yield can be obtained. Operation time is also shortened considerably.
    2) The establishment of process to remove the sulfur from the melt of high sulfur content in the AOD have resulted in the elimination of crude ferronickel's desulfurization step in the alloy section.
    3) Total energy consumption can be saved to a great extent.
    4) High-purity, high-quality stainless steel can be produced constantly.
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  • Ikuo YARITA, Kunio KITAMURA, Masanori KITAHAMA, Kenji KATAOKA, Kichiza ...
    1981 Volume 67 Issue 14 Pages 2152-2161
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Heat streaks are surface defects which often occur in cold rolling of thin gauge steel strip. Rolling conditions influencing the heat streak formation have been investigated using the commercial rolling mills. The mechanism of heat streak formation was revealed by microscopic observation of work rolls and rolled strip surface, and by analysis of oil film conditions in contact arc using elastohydrodynamic lubrication theory.
    The summaries are as follows;
    (1) Grinding scratches on a work roll form heat streaks in each case of heavy reduction rolling, high speed rolling, rolling of hard meterial and cooling with an insufficient coolant flow rate.
    (2) Grinding scratches extremely increase oil film pressure and temperature around the scratches. When the oil film breaks out due to the increase of pressure and temperature, heat streaks occur.
    (3) Two effective countermeasures were obtained. The first is to control the size of roll surface defects under 3 μm, and the second is to use rolling oil of high boundary lubricity which can endure high pressure and temperature.
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  • Kotobu NAGAI, Koji SHIBATA, Toshio FUJITA
    1981 Volume 67 Issue 14 Pages 2162-2171
    Published: 1981
    Released: June 19, 2009
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    Effects of manganese on low temperature mechanical properties have been studied in carbon-free 11Ni-1Mo-Mn steels. Charpy impact tests were performed at temperatures between 0°and about -255°C. A manganese free steel revealed intergranular failure in the as-quenched condition, and the sulfur segregation to austenite grain boundaries may be responsible for this embrittlement. This phenomena could be easily eliminated by the addition of only 0.5 pct manganese. However, as the manganese content increased more intergranular embrittlement during reheating prevailed. The grain boundary segregation of nickel and manganese might be closely concerned with the mechanism of the embrittlement.
    The fine-grained 0.5 pct manganese steel showed the most excellent low temperature toughness and revealed no brittle feature in Charpy tests at about -255°C when it was reheated at temperatures between 550°and 650°C.
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  • Tsuneaki SAKAKI, Kohichi SUGIMOTO, Ohmi MIYAGAWA
    1981 Volume 67 Issue 14 Pages 2172-2181
    Published: 1981
    Released: June 19, 2009
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    The characteristics of plastic deformation of 1 700 N/mm2 grade maraging steel were revealed from the precise true stress-true strain curves and the strain hardening rate-true strain curves, and from the observation of dislocation structure. The factors affecting the uniform elongation were discussed.
    1) The plastic deformation was mainly composed of the four kinds of fundamental stages.
    2) In the solution-treated or under-aged steels, the plastic deformation was composed of the first stage which was affected by the martensite transformation and by the aging, and of the third and the fourth stages with linear hardening. The uniform elongation of these steels was determined by the character of the first stage.
    3) In the over-aged steels, the second stage with high strain hardening rate due to coarse precipitate particles appeared, and so the uniform elongation increased largely.
    4) The reverted austenite precipitated in over-aged steels increased slightly the uniform elongation.
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  • Yasuhiro MAEHARA, Tatsuro KUNITAKE, Nobukatsu FUJINO
    1981 Volume 67 Issue 14 Pages 2182-2190
    Published: 1981
    Released: January 18, 2010
    JOURNALS FREE ACCESS
    The dynamic recrystallization behavior of austenite was studied using an 0.11C-1.0Mn steel (B) and two Nb steels containing 0.02Nb-0.10C-1.0Mn (K8) and 0.02Nb-0.01C-1.0Mn (K12) by analyzing stress-strain (σ/ε) curves obtained by hot tensile deformation at temperatures (T) of 8501 100°C and at strain rates (ε) of 10-410-1 s-1. The peak stress (σp) in the σ/ε curve, observed under the dynamic recrystallization, was larger in the order of the steels K8, K12 and B. In the steels B and K12, σpwas correlated with T and ε by the following equation; ε=A σnpexp(-Q/RT). The value of Q was 59.3 and 69.3 kcal/mol for the steel B and K12, respectively and that of n was about 5.0 for both steels. In the steel K8, the Arrhenius plot had two slopes, in which larger one in the lower temperature range gave Q=85.6 kcal/mol. These phenomena can be explained by the precipitation behavior of Nb(C, N). Strain to peak stress (εp), which is usually taken to be the strain for the dynamic recrystallization, increased by Nb addition. In the steel K8, the recrystallization of the specimen deformed after solution treatment was remarkably retarded at a specific strain rate for a given deformation temperature, e.g. 10-3_??_ε_??_10-1 s-1 at 900°C. This can be explained by the precipitation of fine Nb(C, N) particles during deformation. It was observed that the retardation was much smaller in the case of the steel K12. This was ascribed mainly to solid solution of niobium.
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  • Hiroshi KOBAYASHI, Haruo KAJI, Yutaka KASAMATSU
    1981 Volume 67 Issue 14 Pages 2191-2200
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The formation kinetics and the growth rate of proeutectoid ferrite (p.f.) have been examined by means of optical microscopy in commercial low carbon high strength steels containing Nb(0.04-0.08 wt%) and V(0.10 wt%) at temperatures ranging from 640°C to 700°C.
    The growth of p.f. immeadiately after solution treatment is remarkably retarded by a small amount of Nb addition. In contrast, V addition rather promotes it. The nucleation is also dramatically supressed by Nb, but not so much by V. The precipitation of Nb(C, N) from austenite increases both the growth and the nucleation rate of p.f.
    The growth of p.f. containing Nb and V in solution has been discussed in terms of their carbide forming potential and variation of Ae3 temperature with their additions. The effects of Nb and V can be explained by the "impurity drag" model and "no-partition Ae3" concept, respectively. The acceleration of p.f. reaction resulting from Nb(C, N) precipitation is tentatively ascribed to the reduction of C and Nb atoms in solution. The "pinning" effect of Nb(C, N) particles appears to be relatively small on the growth retardation of p.f.
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  • Takayoshi KASUGAI, Akira OKADA, Michio INAGAKI
    1981 Volume 67 Issue 14 Pages 2201-2207
    Published: 1981
    Released: June 19, 2009
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    Metallographic changes in the weld heat-affected zone (HAZ) for the ferritic and pearlitic steel such as Steel SM50 were investigated, and a maximum temperature at any portion of the HAZ was estimated from the relation between microstructual changes and the theoretical formula for one dimentional thermal conduction. Results are as follows;
    (1) The observation of the fusion line was facilitated through the application of an interference microscope to the weld zone etched with the saturated picric acid solution containing an anion activator.
    (2) The massive ferrite at the portion heated to 950°C in the synthetic HAZ with a cooling time from A3 to 500°C of about 0.84 sec, was not the ferrite retained in the base metal, but the ferrite grown from the austenite due to heating.
    (3) The boundary between the HAZ and the unaffected zone of the base metal was clarified by the observation of macro- and microstructures.
    (4) The maximum temperature at any portion of the HAZ was estimated by using an equation introduced from the formula for one dimentional thermal condition due to the instantaneous plane heat source and the metallographic techniques as mentioned above in (1) and (3).
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  • Hidenori SHIRASAWA, Hiroshi KOBAYASHI, Jiro JIZAIMARU
    1981 Volume 67 Issue 14 Pages 2208-2215
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    Effects of different strengthening factors such as ferrite grain refinement, solid solution element, pearlite volume fraction, and transformation micro-constituent on ductility were investigated in order to find the most desirable strengthening method for high strength steel with good ductility.
    Carbon, silicon, manganese, and chromium contents were independently changed in C-Si-Mn steel. Ferrite grain sizes were varied in the range of d-1/2=410 by annealing the hot rolled or cold rolled sheets at temperatures between 600°C and 1 100°C. Strengthening by solid solution and pearlite volume fraction (carbon content) was investigated at the same grain size. Transformation micro-constituent was continuously changed from ferrite·pearlite to bainite by holding the austenitized sheets in salt bath kept between 300°C and 650°C for long enough to finish transformation. Strength and total elongation of these materials were investigated.
    Ferrite grain refining was the most desirable strengthening method because it enhanced strength and elongation. Strengthening by the others were accompanied by decrease in elongation though its degree was different with each other. Solid solution strengthening by Si showed least decrease in elongation, followed by strengthenings by pearlite volume fraction and by solid solution of Mn. Strengtheningby the transformation micro-constituent was not desirable for ductility. Solid solution of Cr was not effective in strengthening.
    Improvement in ductility by ferrite grain refining is due to the increase in local elongation. Decrease in ductility by the other strengthening methods is largely influenced by the decrease in uniform elongation.
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  • Toshiro KOBAYASHI, Hitoshi MATSUBARA, Yoshisada UEDA
    1981 Volume 67 Issue 14 Pages 2216-2225
    Published: 1981
    Released: May 07, 2010
    JOURNALS FREE ACCESS
    Instrumented Charpy impact test becomes more useful by connecting the digital memory and microcomputer, in which yield load(Py), maximum load(Pm), pre-maximum load energy(Ei)and post-maximum load one(Ep) are automatically and rapidly analyzed. In this analysis, cyclic oscillations in a load signal are corrected and smoothened by using a method of moving averages(the nonrecursive low pass digital filter).
    Dynamic, JIC value(JId)of A533B steel can be measured a fatigue pre-cracked type Charpy specimen, provided that a true deflection of specimen and a true crack initiation point the load-deflection curve are known. For this purpose, elastic compliance values of the testing machine and the specimen are measured dynamically by the elastic low blow test to correct the apparent deflection. Crack iniitiation point, on the other hand, is detected by the plastic low blow test. It is shown that the crack initiation in the fatigue pre-cracked specimen of this material occurs prior to the maximum load, and that the relation between crack initiation energy(EΔa)and pre-maximum load energy(Ei)is EΔa/Ei≅0.8.
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  • Youichi NAKAI, Yasuji UESUGI, Hayao KURAHASHI
    1981 Volume 67 Issue 14 Pages 2226-2233
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    To develop a laboratory test method for accelerating stress corrosion cracking (SCC) of steels in liquid ammonia, effects of ammonia contaminants, such as O2, N2, CO2, etc., and electro-chemical polarization on the time to failure of specimen under a constant tensile load have been studied.
    SCC is strongly accelerated by an anodic polarization of steel in liquid ammonia which is saturated with CO2 and contaminated with O2 above 0.5 atm partial pressure. By this test method, previous research findings on the inhibition of SCC by the addition of water and the decrease of temperature are confirmed.The susceptibility for SCC of various commercial steels examined by this method for 7 days is correlated very well with the result of one year immersion test in ammonia storage tank. Cracks of specimens are quite similar in appearance and this suggests the same SCC mechanism prevails in both cases.
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  • Youichi NAKAI, Yasuji UESUGI, Hayao KURAHASHI
    1981 Volume 67 Issue 14 Pages 2234-2241
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
    The mechanism of stress corrosion cracking (SCC) of low alloy steel in liquid ammonia has been investigated by measuring potentiostatic polarization curve, potential- or current-time curve under a constant tensile load and electro-chemical hydrogen permeation.
    The results obtained are as follows;
    1) In liquid ammonia containing strong electrolyte, such as NH4NO3, anodic polarization curve of steel shows active, passive and trans-passive states as in aqueous solutions. The passive state is eliminated by the addition of CO2.
    2) By the existence of CO2 in liquid ammonia the corrosion rate of steel increases, and a corrosion product film is formed on the surface of steel. The film formation is considerably accelerated by the addition of O2.
    3) A potential rise or current decay in the constant load test under anodic polarization is observed before the failure of specimen, this indicating the growth of the corrosion product film on the surface of steel.
    4) The addition of water or the decrease of temperature inhibits the formation of corrosion product film and the cracking of specimen.
    5) Under anodic polarization, no hydrogen permeation is observed but cracking is stimulated.
    These results indicate that SCC of steel in liquid ammonia is due to an active path corrosion mechanism.
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    1981 Volume 67 Issue 14 Pages 2242-2246
    Published: 1981
    Released: June 19, 2009
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  • 1981 Volume 67 Issue 14 Pages 2243-2243,2446
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...
    1981 Volume 67 Issue 14 Pages 2253-2256
    Published: 1981
    Released: June 19, 2009
    JOURNALS FREE ACCESS
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