Microanalysis of Oxide Layers of Steels

Shiraiwa, Toshio; Fujino, Nobukatsu; Matsuno, Fumio

doi:10.2355/tetsutohagane1955.54.4_534

Cited by 7 publications

(11 citation statements)

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“…The black layer near the surface was composed of hematite and magnetite, and the following gray layer composed of wüstite. It should be noted that wüstite is dissociated 11,13) into magnetite and Fe below 843 K. 12) EPMA analysis shows that the black angular particles in the gray layer of Fig. 2 represent magnetite.…”

Section: Oxidation Of Iron Samplesmentioning

confidence: 99%

Effect of Iron Substrates on Reduced Porous Morphologies Adequate for Unusual Wetting

Takahira

Tanaka

2007

Mater. Trans.

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The authors have found that liquid metal droplets wetted and spread very widely on solid iron substrates in a reducing atmosphere after the surface oxidation of the specimens. This unusual wetting is caused by capillary penetration into the porous layer formed on the iron sample that is reduced after first being oxidized in air. In order to find adequate conditions for the unusual wetting behavior, the effect of the underlying iron substrate on the reduced porous morphology of the oxidized Fe layer has been investigated. Pores in the porous iron layers of all samples formed on iron substrates are 3-dimensionally inter-connected, while those of the porous iron films of some samples without underlying iron substrates were partially isolated and not entirely connected within the films. Adequate porous iron layers that show this unusual wetting behavior were obtained mainly from reduction of the oxidized iron layer formed on the surface of iron substrates rather than from reduction of the oxidized iron films formed without underlying iron substrates.

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Section: Oxidation Of Iron Samplesmentioning

confidence: 99%

Effect of Iron Substrates on Reduced Porous Morphologies Adequate for Unusual Wetting

Takahira

Tanaka

2007

Mater. Trans.

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“…..... (2) ........ (3) Precipitation of magnetite results in the first stage with the formation of a meta-stable iron-rich Fe 1-y O. Then, transformation of the iron-rich Fe 1-y O to magnetite and metal iron proceeds in the second stage.…”

Section: Introductionmentioning

confidence: 99%

“…According to the literature, incubation time of 100 s and more was required to start the reaction. 2,6,9,10,12,13) Isothermal transformation temperature and possibly the prior scaling temperature affected the incubation time. Transformation of a bulk FeO (free from the base metal) was studied by Chaudron and his coworkers at below 843 K. [4][5][6] They indicated that the rate of transformation had a maximum at 753 K (480°C), 4) and the liberated iron dissolved in the remaining FeO and increased its lattice constant.…”

Section: Introductionmentioning

confidence: 99%

“…was examined for isothermally annealed wüstite scale at below 843 K. 2,[4][5][6][7][8][9][10][11][12][13] The rate of this eutectoid reaction was reported the fastest at 673-753 K (400-480°C); it may depend on the scaling temperature, composition of the parent FeO, etc. According to the literature, incubation time of 100 s and more was required to start the reaction.…”

Section: Introductionmentioning

confidence: 99%

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In-situ Measurements of Isothermal W^|^uuml;stite Transformation of Thermally Grown FeO Scale Formed on 0.048 mass% Fe by Synchrotron Radiation in Air

et al. 2013

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Isothermal wüstite transformation of thermally-grown FeO scale formed on 0.048 mass% Fe at 948 K for 180 s and annealed at 673, 723 K, and 773 K in air was studied in situ by synchrotron radiation. Wüs-tite transformation initiated right at the beginning of isothermal heating, either by the formation of a new phase of meta-stable iron-rich wüstite (at 673 and 723 K) or by direct transformation to magnetite (at 773 K). At 673 K, iron-rich wüstite replaced the parent wüstite thoroughly, and then transformed to magnetite and metal iron. At 723 K, formation of the iron-rich wüstite started as well, but the reaction was interrupted and was replaced by a gradual enrichment reaction of iron in both the parent and the iron-rich wüstite phases. Consumption of the parent wüstite and generation of magnetite accompanied. Wüstite transformation to generate magnetite and metal iron at 673 and 723 K was only possible for the iron-rich wüstite. At 673 and 723 K, incubation time was needed to initiate transformation of meta-stable iron-rich wüstite to magnetite and metal iron. Reaction to form the iron-rich wüstite from the parent wüstite was much easier. Tranformation of the iron-rich wüstite to magnetite and metal iron is considered a root cause for the formation of the lamellar structure and the magnetite seam in the scale. The transformation can well be interpreted from the analogy of the formation of the pearlite structure in steels.

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“…Thus, numerous efforts have been made to control the composition of the non-metallic inclusions in molten steel [1][2][3][4][5][6] and the morphology of inclusions in solid phase steel. [7][8][9][10][11] The behavior of non-metallic inclusions in solid phase steel has been investigated mainly for Si-killed steel. Ohshiro et al reported that control of the composition of the inclusions to make them easily deformable during hot rolling was effective in improving the reliability of high fatigue spring steel.…”

Section: Introductionmentioning

confidence: 99%

Effect of Li2O Addition on Crystallization Behavior of CaO–Al2O3–MgO Based Inclusions

et al. 2011

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The crystallization behavior of CaO-Al2O3-MgO oxide powder which is one of the major non-metallic inclusions in Al-killed steel was systematically examined in the present study. 33mass%CaO-62mass% Al2O3-5mass%MgO and 30mass%CaO-57mass% Al2O3-5mass%MgO-8mass%Li2O glass powders were heat-treated at 1 073-1 673 K for 8-512 s under air.CaO-Al2O3-MgO glass was found to be crystallized immediately after the heat treatments. Moreover, it was revealed that the addition of Li2O accelerated the crystallization of the glass powders, and controlled aggregation of crystal particles. Additionally, the indentation hardness of crystallized glasses after 512 s heat-treatments was investigated by using a nano-indenter. The addition of Li2O had the effect of lowering the hardness of samples, which indicates that Li2O would improve the deformation behavior of aluminate based inclusions.

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Microanalysis of Oxide Layers of Steels

Abstract: The scales formed on the steels are examined through the electron probe microanalysis. Examined steels are low carbon rimmed steel, silicon killed steel, weather-resistance steel, high strength steel, sulfer free-cutting steel, ferritic and austenitic stainless steels.

Cited by 7 publications

References 1 publication

Effect of Iron Substrates on Reduced Porous Morphologies Adequate for Unusual Wetting

Effect of Iron Substrates on Reduced Porous Morphologies Adequate for Unusual Wetting

In-situ Measurements of Isothermal W^|^uuml;stite Transformation of Thermally Grown FeO Scale Formed on 0.048 mass% Fe by Synchrotron Radiation in Air

Effect of Li2O Addition on Crystallization Behavior of CaO–Al2O3–MgO Based Inclusions

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