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[in Japanese]
1972 Volume 58 Issue 14 Pages
1925-1926
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Nobuo TSUCHIYA, Masanori TOKUDA, Masayasu OHTANI
1972 Volume 58 Issue 14 Pages
1927-1939
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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As one of a series of experimental studies designed to establish the mechanism of Si transfer in the blast furnace, siliciation of iron and iron-carbon melt by SiO gas has been investigated in the temperature range from 1500 to 1670°C.
The mechanism of Si transfer proposed in this work indicates that the adsorption phenomenon on the surface of molten iron plays an important role in the reaction involved. It is also concluded that the reaction velocity is very fast.
The content of Si in iron transferred from SiO gas under the industrial blast furnace condition is estimated by the rate equation obtained in this experiment.
The calculated values are in good agreement with the Si content of pig iron produced from the industrial blast furnace.
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Yasuji KAWAI, Hidetoshi NAKAJIMA
1972 Volume 58 Issue 14 Pages
1940-1950
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Dephosphorization of liquid iron by solid lime was studied by melting metals containing phosphorus in lime crucibles under gas flows of H
2O-H
2-Ar, H
2O-Ar and O
2-Ar. The rate of reaction was determined by the chemical analysis of samples taken from the bath at appropriate intervals. The results obtained were as follows:
i) Dephosphorization reaction proceeded at nearly constant rate.
ii) The rate of dephosphorization increased with increase of the oxygen potential of gases. Effect of the temperature on the reaction rate was weak.
iii) At low
PH2o/PH2 ratio of gas mixtures phosphorus and oxygen contents changed during a run along the equilibrium with solid tetracalciumphosphate and calcium oxide, but at higher ratio those were higher than equilibrium values.
iv) Under present experimental condition, the rate of dephosphorization was determined by the rate of oxygen supply from gas to the liquid iron.
v) In the case of metals containing carbon, decarburization preferentially occurred prior to dephosphorization due to the differeaces of the reaction surface and of the affinity to oxygen.
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Masahiro SHINMEI, Nobuaki KONISHI, Kichizo NIWA
1972 Volume 58 Issue 14 Pages
1951-1960
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Kinetic study of CO reaction during floating zone melting of steel was carried out with rimmed steel samples and Fe-C-0 alloys. The reaction rate strongly depended on oxygen content but had no correlation to carbon concentration, and to oxygen-carbon concentration product. The reaction mechanism was discussed as a heterogeneous reaction at gas/liquid and at solid/liquid interfaces. Melting in an inert atmosphere such as in Ar promotes the reaction at liquid surface (gas/liquid interface), which plays an improtant role in decarburization of steel during floating zone melting. The influences of sample radius and zone traveling velocity are well explained with the oxygen diffusion control mechanism. The effective distribution coefficient of solute elements under the condition of “non-conservative freezing” was considered
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Kiyokazu OGAWA
1972 Volume 58 Issue 14 Pages
1961-1968
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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This study deals with the gas atmosphere heat treatment of high speed steel.
The hardening of the high speed steel is made at the temperature of 1200°C or above, during which the gas of the proper nature forming the atmosphere is worked into, and the hardening and weak carburization are affected simultaneously, and thus the hardness of the steel surface is brought upward, which is the ob-jective.
In order to improve the machinability and durability, efforts have been exerted in America and European countries of late to increase the carbon contents of various kinds of standardized steels, and the effectiveness of the efforts is being recognized. However, this way of thinking, viewed from the points of the equilibrium diagram of steel and of the technical practice, may have narrow limits. This study aims at the rise of the hardness by means of letting the gas atmosphere react and weak carburization take place at the time of hardening.
First of all, selection of the proper gas atmosphere was made going through preliminary experiments of extensive coverage. As a result, itis established that the carburization mechanism at a high temperature of 1200°C and above, entirely unlike the reaction at or around 930°C that is usually employed functions the other way, and the following result was obtained:
(i) The CnHm family gas or its mixture that is usually adopted to form the gas atmos phere does not meet the requirement.
(ii) It is confirmed that the gas atmosphere of weak carburization trend formed with the CO+N
2 family is suitable for the purpose.
(iii) As had been expected, the surface hardness of the high speed steel of HrC 66-67.5 was obtained.
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Noboru YAMAKOSHI, Tsugio KANEDA, Akio SUZUKI, Eigi NIINA, Yoshichika Y ...
1972 Volume 58 Issue 14 Pages
1969-1983
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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There has been a strong demand for a process where patenting treatment before drawing is omitted with a view to rationalizing and improving efficiency of the production of high carbon steel wires. As a means to meet the demand, a new process named the Direct Patenting Treatment has recently been developed with success.
In this new process, hot rolled wire rods, having been passed through the finishing roll stand, are treated in the cooling zone followed by the treatment in the fluidized bed filled with zilcon sand. Test on the new process has been made with high carbon steel wire and wire for cold heading.
The test results and the characteristics of the process are as follows.
1. The variation in the mechanical properties of coil is very little.
2. Particularly with high carbon steel, it is possible to control tensile strength by means of changing the temperature of fluidized bed.
3. Conventional patenting treatment is not necessary.
4. The processed material has excellent properties concerning pickling, drawing, forming and spheroidizing. The mechanical properties of the wire drawn by this process are excellent too.
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Mitsuyuki KOBAYASHI, Manabu TANAKA, Ohmi MIYAGAWA, Takuro SAGA, Dai FU ...
1972 Volume 58 Issue 14 Pages
1984-1992
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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An investigation was made of effect of cooling procedure after solution heating on the grain boundary reaction of austenitic heat resisting steels with high carbon and nitrogen contents, especially 21-4N steel. For cooling procedure after solution heating, water quenching, air cooling, furnace cooling and direct quenching were used.
It was found that the grain boundary reaction was considerably influenced by these cooling procedures. The grain boundary reaction occurred markedly during furnace cooling without the formation of general precipitates. The amount of grain boundary reaction occurring by ageing treatment decreased with increasing cooling rate from solution temperature, while the amount of general precipitation increased.
It was concluded from this results that general precipitation suppressed appreciably grain boundary reaction. This effect of cooling procedure was attributed to the fact that the dislocation density in specimens increased with increasing cooling rate, and that M
23C
6 precipitated preferentially on dislocations, and could not nucleate in the matrix homogeneously in 21-4N steel. Consequently it is implied that the grain boundary reaction predominates in specimens with low dislocation density, and general precipitation with high dislocation density.
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Hiro-oki NAKAJIMA, Toru ARAKI
1972 Volume 58 Issue 14 Pages
1993-2004
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Impact toughness values of martensite and bainite formed at 350°C and below in 0.34%C- and 0.54% CNi-Cr-Mo steels were compared at equivalent hardness levels, and factors which affect the toughness of both structures were discussed. Transition temperature of bainite lowered with decreasing transformation temperature over a wide range of hardness. Transition temperature of bainite which was formed just above
M5 was similar to that of martensite at high and low hardness levels. But at intermediate tempering temperatures martensite showed lower impact transition temperature than bainite. Upper shelf energy value of bainite transformed at low temperature was slightly higher than that of martensite. Increase of carbon content increased appreciably the transition temperature of bainite, as compared at the same transformation temperature, but the transition temperature of martensite was scarcely varied except at low hardness level. Decrease of transition temperature of bainite was observed, when bainite coexisted with martensite by isothermal transformation below
M5 or by up-quenching treatment to the temperature above
M5. The transition temperature of mixed structures, however, seemed not to decrease below that of martensite. In a 0.54%CNi- Cr-Mo steel, increase of prior austenite grain size caused an increase in the transition temperature of bainite but no change was observed for martensite, although upper shelf energy value was decreased with increase of austenite grain size in both structures. Good correlation was obtained between υ
Tγs and cleavage facet size in the various microstructures.
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Shoichi FUKUI
1972 Volume 58 Issue 14 Pages
2005-2011
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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As a part of study of the influence of metal-structure on the delayed fracture strength of low alloy high strength steel in moist atmosphere, the delayed fracture characteristics in 0-1N-HC1 solution was examined for Cr-Mo-V steel of bainitic structure obtained by isothermal heat treatment, and the structure tempered after the treatment.
At the hardness levels over Hv 350, the delayed fracture limit and the delayed fracture ratio of the materials isothermally transformed were higher than those of the materials conventionally quenched and tempered. Only in the case of tempered at 550°C after isothermal transformation, the daleyed fracture strength decreased by the amount equal to that of the quench-tempered material with the same hardness.
Electron microscopic observation revealed that carbides precipitated densely along the prior austenitic grain boundaries in the steel tempered at 550°C after isothermal transformation. A very small amounts of carbides was observed along the grain boundaries in the steel transformed isothermally, and grain boundary carbides of the steel tempered at the temperature over 600°C were globulized.
The comparison of these results with those of quench-tempered material suggested that the difference in the delayed fracture strength between both materials at the high hardness levels attributed to the difference of the precipitation behavior of carbides along the austenitic grain boundaries.
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Taira NAKANO, Hiroshi KAWATANI
1972 Volume 58 Issue 14 Pages
2012-2024
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Several studies were made in the past on the spheroidization of carbide, however, most of them were on the phenomenology of spheroidization and few of them on the mechanism.
In this paper, we have systematically investigated about the effects of chromium content, pre-treating con-dition, austenitizing temperature and cooling rate in relation to the slow-cooling-method which is used for surface-hardened roll materials. The results are summarized as follows.
1) As the chromium content increases, the volume of carbide in austenite increases, and the austenitizing temperature for complete spheroidization becomes to cover a wide range. The critical carbide number for complete spheroidization in cooling rate of 20°C/hr is found to be 5×10
9/mm
3.
2) The carbide number after spheroidization agrees completely with that in austenite. Therefore it is the retained carbide in austenite that grows during slow cooling.
3) There is a critical cooling rate. The following relationship between the critical cooling rate (
R0) and the mean particle spacing (S) is obtained.
R0= 102×10
-1/S-183.6
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Takayuki NAKAMURA, Toshiro FUKUTSUKA, Yoshiro YAGI
1972 Volume 58 Issue 14 Pages
2025-2033
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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In order to investigate the effects of grain boundaries on the cold-rolling and recrystallization textures, two samples which had different grain sizes of 40μ and 270μ in diameter, were prepared by using a zone-melted high-purity iron. These samples were hot-forged and hot-rolled to the plates of2mm in thickness. These plates were cold-rolled to the sheets of 0.5 mm in thickness by 75% reduction and annealed isothermally at 500°C or 575°C in salt bath. X-ray pole-figure measurements, optical and electron microscopic observations were made for the specimens of as cold-rolled and as annealed conditions.
Cold rolling texture: In the coarse grain specimen two types of fiber texture exist, one has a ‹111› fiber axis parallel to the sheet normal and another has a ‹110› fiber axis parallel to the rolling direction, and the dominant texture component is {111}‹112›.
In the fine grain specimen, texture has a ‹110› fiber axis parallel to the rolling direction and the major component of the texture is {001}‹110›. In the microscopic observation, continuous change of orientation from {001}‹110› to {111}‹110› is often observed in the whole area of specimen.
Recrystallization texture: In the coarse grain specimen, {110}‹001› texture component is preferred and the texture component of near {111}‹112› coexists.
In the fine grain specimen, {111}‹110› texture component is dominant. At the beginning of recrystallization, {111}‹110› recrystallization nuclei in {001}‹110› matrix are found frequently in electron microscopic observation.
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Akira TAKAMURA, Kaname ARAKAWA, Takayoshi TSUBOI, Yasushi Torii
1972 Volume 58 Issue 14 Pages
2034-2039
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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This investigation has been carried out in order to make clear the prot ective nature of rust layers. Measurements have been made of the amount of water-soluble compounds dissolved into rain-water from rust layer for 1 month, exfoliated rust, retained rust and absorbed SO
2 by the rust. The results are summarized as follows:
1) Leaching rate of ferrous and sulfate ions into rain-water and exfoliation rate of rust from specimens decreased with increasing the exposure time.
2) The amount of ferrous ions in water-soluble compounds was found to be equivalent to that of sulfate ions: that is, the water-soluble compound in the corrosion products can be estimated to be FeSO
4 or FeSO
3.
3) Insoluble sulfur compounds gradually accumulated in the rust layers during exposure and such rust layers became inactive for SO
2 in the atmosphere. Further, our laboratory experiments on absorption of SO
2 by rusts indicated that the rate of SO
2 absorption or its re-dissolution in water decreased with increasing the exposure period of the specimen.
4) The corrosion losses of steels were more closely related with the amount of exfoliated rust rather than that of the retained rust or water-soluble compounds.
These results indicate the importance of both chemical and structural study in considering the stability of rust layers on corrosion resistant low alloy steels.
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Kazuo KAWAMURA, Hideaki ITO, Takashi OTSUBO, Tomio TANABE
1972 Volume 58 Issue 14 Pages
2040-2048
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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An attempt has been made to establish the meth od for phase analysis of Te in steel. Te is found in steel to take the forms of MnTe, iron telluride-mainly β-FeTe
0.9, and, in special case of high Te and low C contents, β-FeTe 1.9, and free Te which segregates on cooling from the γ-phase along by pearlite structure; these pre-cipitates of Te compounds (e xcept ε-FeTe1.9 unstudied) can be divided into soluble Te po rtion (MnTe) and insoluble Te portion (β-FeTe
0.9 and free Te) by 2-3N HCl dissolution at room temperature. MnTe canbe det ermined from the difference between total Te and ins oluble Te contents, and by determining Fe andTe, respectively, in the HCl insoluble residue β-FeTe
0.9 and free Te contents can be estimated supposing that any other iron compounds do not exist in the residue.
As a result of the phase analysis of Te in the specimens, the followings were clarified;
1) Te in steel exists predominantly as MnTe, and the relative content of MnTe becomes larger with increasing C content. MnTe may be dissolved by solution treat ment at 1 200°C and after water quenching reprecipitated by heating at 750°C.
2) The ratio of free Te/insol Te becomes larger with inc rease of C content.
3) The segregation of free Te occurs along by pearlite structure and this is thought to result from the difficulty of its dissolution into ferrite and cementite.
4) Loss of Te is not observed through the heat treatment up to 1 200°C
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Tetsuo MATSUMURA, Naomi KOTANI, Takeshi GOTO, Kiichi NARITA
1972 Volume 58 Issue 14 Pages
2049-2059
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Fluorescent X-ray analysis and emission spectrometric analysis (quantovac) were compared each other for the determination of Si, Mn, P, S, Cu, Cr, and Ti in pig iron and a consideration was given to the effects of the metallic structure of a sample on precision and accuracy of the analytical results. The instruments used r for this study were X-ray quantometer VXQ-120, two simultixes and two vacuum quantorecorders. A pair of samples were taken into both steel and sand moulds from a spoon of metal. Some of elements the alibration standards of which were required were added into a spoon for several charges of all 50 samples.
For quantovac analysis, there was little difference in calibration curves between samples of the different moulds, while for X-ray analysis the calibration curves of Si, P, S, and Ti showed some differences which made greater as the atomic number decreased. In the samples of less than 0-40% of Si and/or more than 0.30% of Cr taken into sand mould, whose structures showed white or mottled pig iron structure, analytical values of P and S gave big errors.
Precision was in the same level for X-ray and quantovac analyses for heavy elements, but the former was superior to the latter for P and S by factor of 3 to 5. Accuracy of X-ray system was comparable to that of quantovac system.
It was concluded as the results of this study that fluorescent X-ray analysis was preferable to quantovac system for a production control analysis of pig iron from overall view points.
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Kazuo KAWAMURA, Siro WATANABE, Masahiro YAMADA
1972 Volume 58 Issue 14 Pages
2060-2066
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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A fundamental study has been made on application of the cold HNO
3. method to extraction and analysis of inclusions in steel, particularly in rimmed steel. Potentials in cold HNO
3 media are measured with use of a Pt electrode against saturated calomel electrode, and chemical behaviors of several compounds, in cold HNO
3 are also investigated.
The followings are the results obtained;
(1) The potential in cold HNO
3 is found to vary remarkably around the concentration of (1+1) of HNO
3, thus showing higher value at the higher concentration whereas lower one at the lower concentration, of HNO
3.
(2) Direction of current between pure iron electrode and S. C. E. in cold-HNO
3. cell is observed to be different at the concentrations of (2+1) and (1+1) of HNO
3.
(3) Ferrous iron compounds such as FeO, FeS and FeO-silicate are stable in cold HNO
3, but MnO, MnS and compounds containing much quantity of Mn component are easily attacked by cold HNO
3(4) The cold HNO
3 method is found useful for extraction and analysis of inclusions in steel, having an advantage of choice of adequate concentration and temperature of cold HNO
3 according to the purpose.
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Kazuo KAWAMURA, Shiro WATANABE, Tokio SUZUKI
1972 Volume 58 Issue 14 Pages
2067-2077
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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An investigation has been made on extraction and determination of various precipitates in steel by cold nitric acid method, comparing with other available methods.
The results obtained are as follows:
(1) TiC, TiN, Ti
2O
3 and sulfide of titanium in steel are quantitatively extracted by nitric acid (1+8) at -5°C. TiN is especially stable to cold nitric acid.
(2) ZrC, ZrN and ZrO
2 in steel are quantitatively extracted in a wide range of conditions of cold nitric acid method.
(3) VC and VN in steel are quantitatively extracted by nitric acid (1+8) at -5°C. The vanadium compounds are, however, rather less stable to cold nitric acid, and completely decomposed by nitric acid (1+1) at -5°C.
(4) NbC, NbN, (Fe, Nb) O
2, FeO·Nb
2O
5 and Fe
2Nb in steel are quantitatively extracted by nitric acid (1+1) at -20°C. The niobium compounds are in general stable to cold nitric acid.
(5) Molybdenum carbides in steel-(Fe, Mo)
3C, Mo
2C, (Fe, Mo)
23C
6 and (Fe, Mo)
6C-are unstable to cold nitric acid.
(6) The cold nitric acid method is thus found to be applicable with good reproducibility to extraction. and determination of various precipitates in steel. The time required for extraction is 1-2 hrs under stirring for lg of drillings of the sample.
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Toshio SHIRAIWA, Taiji ARAKI, Nobukatsu FUJINO, Fumio MATSUNO
1972 Volume 58 Issue 14 Pages
2078-2088
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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The origins of large nonmetallic inclusions in continuoulsy cast plain carbon steel billets have been investigated in relation to the mould scums. Three kinds of synthetic scums containing tracer elements of La, Ce or Ca individually are added into the liquid plain carbon steel in the continuous casting mould poured by means of an open nozzel, and inclusions in the billets are analysed in electron prove microanalyser. The results obtained are as follows.
1) In the inclusions larger than about 150μ in diameter, tracer elements are observed, but none in those smaller than about 100μ in diameter.
2) The compositions of large inclusions are similar to those of mould scums.
3) From these results it is concluded that most of large inclusions originate from mould scums.
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Tetsuo TANI
1972 Volume 58 Issue 14 Pages
2089-2094
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Sukeo ODA
1972 Volume 58 Issue 14 Pages
2095-2101
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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Mitsuo IMAI
1972 Volume 58 Issue 14 Pages
2102-2109
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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[in Japanese]
1972 Volume 58 Issue 14 Pages
2110-2111
Published: December 01, 1972
Released on J-STAGE: October 12, 2010
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1972 Volume 58 Issue 14 Pages
2112-2120
Published: December 01, 1972
Released on J-STAGE: December 22, 2010
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