Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 32 , Issue 4
Showing 1-18 articles out of 18 articles from the selected issue
  • Hajime Nakamura, Yoshikazu Kuriyama, Yasuhisa Yamazaki
    1968 Volume 32 Issue 4 Pages 303-308
    Published: 1968
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    A new ultra-high-strength steel of 100 kg/mm2 was developed jointly by the Ishikawajima-Harima Heavy Industries Co., Ltd. and the Yawata Iron and Steel Co., Ltd. Prior to use for structures and pressure vesseles, various weldability tests were undertaken. It has been established that the mechanical properties of the HT-100 steel weld-joint was satisfactory excepting H.A.Z. deterioration, and it is quite comparable to that of commercial heat treated 80 kg/mm2 high-strength steels. Many investigators, have pointed out that there exists a remarkable brittle zone in the weld-heat-affected zone of the heat-treated high tension steel, and such a brittle zone causes deterioration of weld-joint properties. The following conclusions were obtained as the result of investigation.
    (1) Brittleness of HT-100 steel was observed in the results of pressed-notch charpy, notched slow bend, drop weight and weld-joint wide tension tests.
    (2) When weld defects such as under-cut and angular distortion exist tensile strength decreases to below the yield point of HT-100 steel in the weld-joint wide tension tests.
    (3) Successful results in improving for over-all weldment properties were obtained by deposition of a protective weld bead called A.C.I. bead in this investigation. These effects were believed to be due to micro-structure refining, removing of stress consentration at weld toes, and increasing of thickness in the weld-heat-affected zone.
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  • Hajime Nakamura, Yoshikazu Kuriyama, Yasuhisa Yamazaki
    1968 Volume 32 Issue 4 Pages 309-315
    Published: 1968
    Released: April 04, 2008
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    In the preceding paper, the authors reported that a remarkable brittle zone exists in HAZ (Heat-Affected-Zone) of HT-100 steel welded joints. The results of brittle fracture tests showed that brittle cracks always run over the parts of 0.5 to 1.0 mm apart from the fusion line heated to 1150°∼1350°C during welding. Therefore it is important to make clear why HAZ of HT-100 steel shows such a brittle behavior.
    Chemical analysis showed that no remarkable changes in composition were observed across HAZ, and this was also confirmed by an X-ray-microanalyser. The increase of free nitrogen as a result of decomposition of AlN in the steel was though to be not harmful to the embrittlement of HAZ. After various investigations the authors concluded that the embrittlement of HAZ was mainly dependent on the microstructure change due to heating above Ac3 and rapid cooling during welding.
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  • Eiji Takahashi
    1968 Volume 32 Issue 4 Pages 315-319
    Published: 1968
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Strain rate cycling tests have been performed during the tensile deformation in the temperature range 203°∼300°K of polycrystalline iron specimens aged at 200°C, aged at 200°C after straining at room temperature and strained at 200°C to study the influence of strain rate on the flow stress of aged iron. It has been found that the change in flow stress ΔσA associated with a 10:1 change in the strain rate tends to decrease with increasing strain and that the work hardening coefficient does not depend on temperature. The work hardening coefficient of aged iron is smaller than that of iron which is not aged. It is supposed that this decrease is due to the fact that the effective stress of the aged iron mainly decreases with increasing strain, although the effective stress of the unaged iron scarecely depends on the strain.
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  • Yutaka Ono, Yukio Inokuti, F. Eiichi Fujita
    1968 Volume 32 Issue 4 Pages 320-325
    Published: 1968
    Released: April 04, 2008
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    In order to separate the effect of impurities from the inherent process in the precipitation of super saturated carbon in α-iron, super-purity iron specimens were made by zone refining, carburized to 0.009 wt% carbon, and used in the quench aging experiment. The results were compared with the specimens from the same sources (Puron 99.9% and Johnson-Matthey) but not zone refined.
    The precipitation process was followed by measuring the electrical resistivity and internal friction and by the direct observation with the transmission electron microscope. All of the measurements showed appreciable differences between the super-purity specimens and lower purity specimens, as are summarized in the following.
    (1) The precipitation process consisted of two steps, as previously reported(1), showing the formation of a meta-stable phase before that of the cementite phase. For the fact that clear and explainable differences were observed in the first step while they were not always well-interpreted in the second step, only the former step was dealt with in this report.
    (2) The internal friction measurement revealed that for purer specimens the time necessary for the precipitation is shorter. As most of the impurity atoms were considered to be oxygen and no difference in the density of precipitation nuclei was found by electron microscopy, it was quite conceivable that the oxygen atoms do not give rise to the decrease of the nucleation rate but temporarily trap the migrating carbon atoms to make the process delayed.
    (3) In the lower purity iron the aging curves obtained by the electrical resistivity measurement were in fairly good accordance with those by the internal friction measurement, while in the zone melted super-purity iron the resistivity decreased in the order of ten times slower than the C-Snoek peak decay in the first step. It was suggested that in super-purity iron were formed a special configuration of precipitates with a large capacity of scattering the conduction electrons which brings about a considerably large resistivity increase.
    It was concluded that the precipitation phenomena of interstitial elements so far reported in pure iron are not characteristic of the pure state but mostly arise from the impurity effect.
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  • Yukio Inokuti, Yutaka Ono, F. Eiichi Fujita
    1968 Volume 32 Issue 4 Pages 325-328
    Published: 1968
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    In the previous work(1), we have shown, as one of the results, that in super purity α-iron the precipitation curves of super-saturated carbon measured by electrical resistivity are noticeably delayed from those measured by internal friction while they are not appreciably different from each other in the commercially pure iron which usually contains a small amount of oxygen.
    This delay was considered to be arising from an extraordinarily large scattering of conduction electrons from the precipitate particles in the super purity α-iron. On the other hand, there exsisted some doubt if this phenomenon was due to the effect of dislocations; that is, dislocations in the purer specimens might gather more precipitant carbon atoms than in the less pure specimens accelerating the precipitation process and at the same time, form a special configuration of precipitates or agglomeration which has a large scattering power for electrons. Therefore, the precipitation process of carbon in the super pure specimens with a considerably high density of dislocations was examined by the electrical resistivity and internal friction changes.
    The specimens containing about 0.009 wt% carbon were cold-worked to 5% extension after quenching and the precipitation process was followed by the electrical resistivity and internal friction measurements during 132°C isothermal annealings. The precipitation curves obtained by both methods coincide with each other within experimental errors. From this result, we conclude that the scattering of conduction electrons by the precipitates at the dislocation sites must be different in the reversed sense from that of the precipitates in the matrix of super purity α-iron.
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  • F. Eiichi Fujita, Yutaka Ono, Yukio Inokuti
    1968 Volume 32 Issue 4 Pages 328-334
    Published: 1968
    Released: April 04, 2008
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    The effect of addition of a small amount of silicon on the precipitation process of carbon in super-purity iron was examined. The specimens containing 0.02 and 0.2 wt% silicon were made from the zone melted Puron, carburized to 0.009 wt% carbon concentration, and quenched into iced water. The precipitation process during the isochronal and isothermal aging was measured by the electrical resistivity and internal friction. The process was also followed by the direct observation by electron microscopy.
    The obtained results and our conclusions were as follows.
    (1) The precipitation of carbon was presumably delayed by the temporary trapping of migrating carbon atoms by silicon atoms, and the rate of delay is in proportion to the silicon contents.
    (2) This trapping effect was analysed by our theory of precipitation based on the chemical rate determining equations taking account of the impurity interaction, and it was clarified that only the above trapping mechanism feasibly accounted for the delay in the precipitation. Oxygen atoms in α-iron of commercially high purity seem to play the same role as silicon in the process of carbon precipitation, and therefore their effect reported in the previous paper may be analysed by the same theory.
    (3) Like the case of the zone melted super purity iron, the silicon impregnated super purity iron showed large descrepancies between the electrical resistivity and the internal friction decay curves. This behavior is quite different from that found in the lower purity α-iron, and we concluded that the influences of silicon and oxygen in the structure of the metastable first phase of carbon precipitation are dissimilar to each other in spite of the same trapping effect.
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  • Shoji Goto, Shigeyasu Koda
    1968 Volume 32 Issue 4 Pages 334-339
    Published: 1968
    Released: April 04, 2008
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    The oxidation behavior of solid solution nickel-aluminum alloys was studied at decomposition oxygen pressure of NiO. Five alloys containing 1.37, 2.38, 4.29, 6.37 and 6.55 atomic percent Al were oxidized at 900°, 1000°, 1100°, 1200° and 1300°C for 6, 12, 24, 36, 48, 60 and 72 hours. Studies on the subscale penetration, size and distribution of oxide, and Vickers hardness of the internally oxidized layer have been carried out. The results obtained are as follows.
    (1) The relationship between the penetration depth, that is the depth of the internally oxidized layer, and the oxidation time of specimens was well expressed by a parabolic law. (2) Diffusion coefficient of oxygen in the internally oxidized layer was calculated by Wagner’s equation. With increase of the dispersed particles, the diffusion coefficient of oxygen increased and this tendency was increased at lower temperature. It was explained by the interfacial diffusion of oxygen between the nickel matrix and dispersed particles. From these results, the diffusion coefficient of oxygen in pure nickel was obtained. (3) The dispersed particles were of platelet on the {110} matrix planes, and had a dendritic structure. (4) The dispersed particles were of crystalline NiAl2O4. (5) An anomalous oxide band was observed at the internal-oxidation front in internally oxidized alloys with high aluminium. (6) The size of the dispersed particles in the internally oxidized layer increased with the distance from the surface of the specimens, and with increasing solute content, the density of dispersed particles became higher. Accordingly, the Vickers hardness of the internally oxidized layer varied, with the distance from the surface.
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  • Seiichi Nishikawa, Kazuo Nagata, Sigeyoshi Kobayashi
    1968 Volume 32 Issue 4 Pages 340-345
    Published: 1968
    Released: April 04, 2008
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    Decomposition processes of Cu-Co binary supersaturated solid solutions containing 2.85, 1.05 and 0.51 wt%Co, solution treated at 1000°C for 1 hr, have been investigated by electrical resistivity measurements, hardness tests, optical and transmission electron micrographs.
    The results are summerized as follows: (1) Electrical resistivity of 2.85 wt%Co alloy dropped very rapidly in the early stage of high temperature ageing. For example, when aged at 600°C, about 60% of the whole decomposition process had been completed within 10 sec, but without any indication of hardening and any traces of micrographical changes. (2) Increment in electrical resistivity due to solute clustering or zone formation was not observed in the early stage of ageing. (3) Hardening began to appear at a fairly later stage than the electrical resistivity change, and the hardness curve showed only a simple single-peak. (4) As a result of the microscopical observation, it was clarified that in this system both continuous and discontinuous precipitations proceed simultaneously, but the amount of the latter was very small. In the former, sherical Co-rich precipitates completely coherent with matrix grew, but in the latter, normal lamellar precipitates appeared. (5) On the application of such an overall transformation kinetics equation as f=1−exp(−btn), the decomposition process of the Cu-Co supersaturated solid solution was divided into three stages with different n values. But for some reasons, it seemed to be probable that the first and third stages might be put out of the application of the above equation.
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  • Satoshi Hanai, Osamu Akisue
    1968 Volume 32 Issue 4 Pages 345-350
    Published: 1968
    Released: April 04, 2008
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    The effects of AlN on the recrystallization textures in commercial low carbon aluminum killed cold rolled steel sheets were examined using electron microscopy and X-ray diffraction techniques. Final microstructures and textures were found to be related to the holding time and the temperature of heat treatment before cold rolling. The precipitation of AlN before cold rolling gave the tendency to increase the (110)[001] texture and to decrease the (111)[1\={1}0] and (111)[11\={2}] textures after annealing. Electron microscopy indicated that AlN, precipitated on cell walls and dislocations prior to recrystallization, inhibited the subgrain formation. Therefore in aluminum killed steel, the recrystallization seems to occur without such subgrain coalescence as observed in rimmed steel. The effects of AlN precipitated prior to recrystallization on the textures were also discussed.
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  • Sadatoshi Inada, Koichi Uesaki
    1968 Volume 32 Issue 4 Pages 351-356
    Published: 1968
    Released: April 04, 2008
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    The behaviors of precipitates along grain boundaries of vacuum melted copper compressed at elevated temperatures between 650° and 830°C were studied, using furnace-cooled specimens.
    The results were as follows:
    (1) The precipitates particles observed by electron microscope on the surface of the specimens without compression at elevated temperatures were dispersed over the surfaces independently of grain boundaries. The precipitates were so small that they were hardly observed by a hot stage microscope.
    (2) When specimens were kept under low compressive stresses at elevated temperatures, precipitates were observed along grain boundaries not only on surfaces but also in the inner parts of specimens.
    (3) It may be considered that the causes for the results mentioned in (1) and (2) are as follows: Solute atoms transferred in the opposite direction to the vacancy flow segregate on the surface or along grain boundaries which play a role as sources or sinks for vacancies.
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  • Susumu Morioka, Yoshinobu Sawada, Katsuhisa Sugimoto, Tôji Kat&o ...
    1968 Volume 32 Issue 4 Pages 356-362
    Published: 1968
    Released: April 04, 2008
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    Effects of Al2O3 content, worked structure and heat treatment on the corrosion resistance of SAP containing 1.2∼15.5%Al2O3 in pure water at elevated temperatures of 200°∼300°C were studied by measuring the weight gain. Surface corrosion products were analysed by means of electron diffraction and infrared absorption spectra and further observed by electron microscopy. The results obtained are summarized as follows:
    (1) The corrosion resistance of the rolled SAP and the pressed SAP varied with the Al2O3 content and was worst at 3.5∼6.8%Al2O3, while that of the extruded SAP was not affected with its Al2O3 content and was best of the three. (2) The corrosion resistance of the rolled SAP was improved by annealing, while that of pressed SAP could not be improved. (3) The surface film on SAP produced by corrosion was made up mostly with α-Al2O(OH)2 (boehmite) and contained a small amount of γ-Al2O3 resulting from the SAP matrix. (4) The grain size of the surface film was fine for SAP of good corrosion resistance but coarse for that of less corrosion resistance.
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  • Tetsu Oi, Kikuji Sato
    1968 Volume 32 Issue 4 Pages 363-368
    Published: 1968
    Released: April 04, 2008
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    A normalized commercial low carbon steel containing 0.24% carbon was subjected to the tensile test at strain rates (\dotε) of 1.7×10−4, 1.0×10−3, 1.0×10−2 and 1.0×10−1 sec−1 for 5.0±0.2% of plastic deformation (ε) to investigate the strain rate dependence of dislocation density and its distribution, and was strained at \dotε=1.0×10−3 sec−1 for ε=20% to investigate the cell structure.
    The results are as follows:
    (1) The average dislocation density is 1.9×1010 cm−2 after 5% deformation, independent of the range of strain rates examined.
    (2) The faster the strain rate, the less frequently are found grains which contain cell structures. A cell structure is found almost in every grain when \dotε=1.7×10−4 sec−1, while only a uniform distribution of dislocations is observed when \dotε=1.0×10−1 sec−1. At the intermediate strain rate, cell structures are observed in the grains as frequently as uniform distribution of dislocations.
    (3) The cell walls are arranged into a grid-like pattern after 20% deformation, and their planes seem to correspond to one of {110}, {112} and {123} crystallographic planes.
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  • Hitoshi Nakae, Akira Okada
    1968 Volume 32 Issue 4 Pages 368-374
    Published: 1968
    Released: April 04, 2008
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    In the early stage of the recrystallization process in a cold rolled (96% reduction in thickness) Ni-Fe alloy sheet, it was observed by transmission electron microscopy that the cube-oriented grains were grown mainly in regions adjacent to the band-like structures in the rolling texture which consisted of (110)[1\={1}2] and (100)[001] components. On annealing at 490°∼500°C for 30 min, a high dislocation density region remained in slightly grown cube grains. Such a region was contained at only one site in each cube grain, and its size was comparable with that of the subgrains. It was presumed that the region was the origin of the cube grain, but it was neither the region where any dislocation reactions such as the inverse Rowland transformation had taken place, nor resulted from any impurity effects.
    It was concluded that the cube grains grew preferentially from the cube components which already existed in the rolling texture.
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  • Kazuo Kawamura, Shiro Watanabe, Tokio Suzuki
    1968 Volume 32 Issue 4 Pages 375-378
    Published: 1968
    Released: April 04, 2008
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    In order to establish a method of phase analysis of vanadium, a study has been made of the chemical behavior of vanadium compounds synthesized. Extraction of vanadium compounds from steel was satisfactorily carried out in cold HCl; the extract was found to be almost carbonitride by an X-ray diffraction technique. Electron microscopic observation proved the existence of very fine precipitates of vanadium compounds (smaller than 0.3 μ). A recommended procedure for a phase analysis of vanadium in steel is as follows: The sample is decomposed in cold HCl at room temperature. The residue (acid insoluble vanadium fraction) is filtered and treated with HClO4-H2O2, and then vanadium as carbonitride is determined from the solution and vanadium as nitride from the insoluble residue. The experimental results showed that more than a half of vanadium in steel was solid soluble one which belonged to the acid soluble vanadium fraction, and that the acid insoluble vanadium fraction consisted mainly of carbonitride. Small amounts of nitride and oxide were also recognized.
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  • Tsutomu Yanagase, Yukio Suginohara, Kiyonori Nakamura
    1968 Volume 32 Issue 4 Pages 379-385
    Published: 1968
    Released: April 04, 2008
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    Studies on the solid-solid reaction of the metallic oxides are of great importance not only for approach to the mechanism of sintering, but also in the field of extractive metallurgy for slag formation. In this paper, the reaction between solid PbO and SiO2 was observed by means of differential thermal analysis with the aid of X-ray diffraction analysis and infrared absorption spectra. It was found that the 2PbO·SiO2 compound appeared at the begining of the reaction, and then PbO·SiO2 or 4PbO·SiO2 compound was formed in accordance with the content of SiO2 in the mixture. Moreover, the activation energy for diffusion of PbO in the silicate was determined from the relation between the temperature of heat treatment and the reaction rate calculated by applying Carter’s equation.
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  • Norio Nagata, Susumu Yoshida
    1968 Volume 32 Issue 4 Pages 385-390
    Published: 1968
    Released: April 04, 2008
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    The strain rate and temperature dependence of the flow stress of copper (99.99% purity) and copper-manganese (0.1∼1.1 wt%) dilute alloy single crystals with the orientations suitable for easy glide has been investigated by compression tests over the strain rate range of 10−4 to 103 sec−1 and the temperature range of 77°K to 373°K.
    The critical resolved shear stress (CRSS) at room temperature gradually increases with increasing strain rate over the low strain rate range, but rapidly increases over the high strain rate range. At low strain rates the CRSS increases with decreasing temperature and increases nearly in proportion to the atomic concentration of manganese. On the contrary, at high strain rates the CRSS for pure copper and 0.1%Mn alloy scarcely varies with temperature, but rather tends to increase with increasing temperature. However, for 0.5% and 1.1%Mn alloys it decreases with increasing temperature. The manganese concentration dependence of the CRSS at low strain rates and its temperature dependence at low temperatures are well explained by Friedel’s solid solution hardening theory. The temperature dependence for 0.5% and 1.1%Mn alloys at high strain rates is also explained qualitatively by the same theory. It is considered that the strain rate dependence in the low strain rate range is controlled by the non-conservative motion of jogs on moving dislocations. On the contrary, for the explanation of the magnitude and the strain rate dependence of the CRSS for pure copper and 0.1%Mn alloy in the high strain rate range, the frictional resistance against moving dislocations from the crystal lattice should be taken into consideration. It is also presumed that the frictional resistance contributes considerably to the deformation of 0.5% and 1.1%Mn alloys crystals at high strain rates.
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  • Kô Soeno, Tetsurô Kuroda
    1968 Volume 32 Issue 4 Pages 391-396
    Published: 1968
    Released: April 04, 2008
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    The kinetics of beta-phase decomposition and the precipitation of alpha-zirconium were investigated by mesuring the change in electrical resistivity at liquid nitrogen temperature. Studies on the reaction in the miscibility gap region were carried out by rapidly heating the specimens which were previously quenched from 1200°C or cold-worked after the quenching. The kinetics of the decomposition are conveniently described with T-T-T curves extending from 650°C to 800°C. It is evident that there is a general acceleration of the decomposition in the cold-worked specimens. For example, the 50 per cent decomposition lines in 25 to 75 per cent cold worked specimens are displaced to about 1/10 of that for the specimens quenched from 1200°C.
    In order to investigate the precipetation of alpha-zirconium, specimens after about 75 per cent beta-phase decomposition, heated at 750°C for 46 hr after 75 per cent cold drawing, were used and the reaction rate was measured between 400°C and 500°C. The time required to attain about 95 per cent of the transformation were about 103 min at 500°C and about 6×103 min at 400°C. The acceleration of the precipitation by cold work are also shown in the specimens cold-worked after the beta-phase decomposition treatment.
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  • Masao Ibaraki, Taira Okamoto, Hiroshi Matsumoto
    1968 Volume 32 Issue 4 Pages 396-402
    Published: 1968
    Released: April 04, 2008
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    A study was performed to make clear the influences of the freezing condition and the carbon content on the structure of metastable iron-carbon alloys frozen unidirectionally in a mold with a copper chill block. The carbon content of these alloys was within a range from 2.4% to 4.7%. The results obtained are as follows: (1) The width between the stalks of cellular dendrite of primary austenite in the hypo-eutectic alloys is inversely proportional to the square root of the cooling rate at the beginning of freezing of primary austenite and is independent of the carbon content. (2) The dendrite arm-spacing of primary austenite is inversely proportional to the fourth root of the cooling rate at the beginning of freezing of primary austenite and to the square of the carbon content. (3) The colony size of ledeburite is inversely proportional to the square root of the cooling rate immediately after the freezing of ledeburite. (4) The minimum lamellar spacing of ledeburite is inversely proportional to the square root of the freezing rate of ledeburite and is larger than that of ledeburite grown in a steady state. (5) The growth mode of ledeburite which is one of lamellar eutectics differs from that of ordinary lamellar eutectics, in which the lamellae tend to grow normal to the developing cellular solid/liquid interface. The lamellae in ledeburite grow straight without changing in the growth direction even for the cellular interface. In such a growth mode, the lamellar structure becomes unstable at the locally undercooled region and the branching of rodlike austenite from the lamellae must occur at the position near the colony boundaries.
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