鉄と鋼
Online ISSN : 1883-2954
Print ISSN : 0021-1575
ISSN-L : 0021-1575
早期公開論文
早期公開論文の27件中1~27を表示しています
  • 松山 嗣史, 奥田 晟生, 安田 天, リム リーワ, 辻 幸一
    原稿種別: 論文
    論文ID: TETSU-2024-017
    発行日: 2024年
    [早期公開] 公開日: 2024/05/22
    ジャーナル オープンアクセス 早期公開

    In this study, we obtained elemental distributions around the scratch in reinforced concrete. Confocal micro-X-ray fluorescence (CM-XRF) technique was employed for observing a sample cross section without destroying the sample. We prepared a rebar fragment, and then it was covered with concrete. The test sample was scratched with the band saw with a blade of ~1 mm width. The scratched test sample was measured using a laboratory-made CM-XRF instrument. As for the Ca distribution, the thickness of the concrete layer was estimated to be ca. 100 μm. In addition, the depth and width of a scratch were calculated to be ca. 150 μm and 1.1 mm, respectively, as observed from the Fe distribution. And then, we observed the corrosion products resulted by immersing the reinforced concrete in NaCl solution. Sphere-shaped structures were seen in the Fe and Cl distributions, therefore, we considered that it to be the corrosion product containing iron chloride. It is expected that by using a sample cell for in-situ observation, it will be possible to observe the corrosion process of reinforced concrete in real time.

  • 田邉 匡生
    原稿種別: 論文
    論文ID: TETSU-2024-039
    発行日: 2024年
    [早期公開] 公開日: 2024/05/16
    ジャーナル オープンアクセス 早期公開

    A spectral measurement system using a sub-THz source in the bandwidth up to 100 GHz, obtained by multiplying and amplifying a frequency-variable signal in the GHz band operated by a silicon semiconductor device, was constructed in conjunction with a frequency-tunable single-frequency THz source using GaP, which has been developed previously, in a transmission and reflection optical arrangement. The absorption spectra of ferrous corrosion products and the reflective imaging of metal fragments hidden behind concrete plate were measured. These results of the sub-THz and THz waves suggest that the interior of building structures can be inspected non-destructively based on the dielectric constant-based absorption and reflection of corrosion products and metals inside the concrete and metal surface under coating respectively, which have a high transmission property.

  • 上村 直紀, 千葉 隆弘, 齋藤 圭, 高井 健一
    原稿種別: 論文
    論文ID: TETSU-2024-051
    発行日: 2024年
    [早期公開] 公開日: 2024/05/16
    ジャーナル オープンアクセス 早期公開

    Crack initiation and propagation behavior in hydrogen embrittlement fracture of tempered martensitic steel at a low hydrogen content was compared with the results at a high hydrogen content. Notched specimens charged with a low hydrogen content of 0.18 ppm and a high hydrogen content of 5.3 ppm were stressed and unloaded immediately upon reaching the maximum stress in tensile tests. At the low hydrogen content, quasi-cleavage (QC) fracture was dominant at the notch tip, and mixed intergranular (IG) and QC fractures were observed away from the notch tip. A crack initiated in the prior γ grains at the notch tip and propagated along the {011} plane. The crack initiation site corresponded to the site of maximum equivalent plastic strain. The other crack initiating on the prior γ grain boundaries was observed at a site away from the notch tip. Microvoids were formed discontinuously inclined at about 45° to the tensile axis direction between these two types of cracks observed at the low hydrogen content. In contrast, at the high hydrogen content, cracks initiated on the prior γ grain boundaries away from the notch tip. The crack initiation site corresponded to the vicinity of the region where both the principal stress and hydrogen concentration were high. These findings indicate that crack initiation at the low hydrogen content is not necessarily consistent with the site of the maximum principal stress and the local hydrogen concentration, unlike the case of the high hydrogen content.

  • 西野 凌平, 田中 友基, 上宮田 和則, 森下 浩平, 宮原 広郁
    原稿種別: 論文
    論文ID: TETSU-2023-119
    発行日: 2024年
    [早期公開] 公開日: 2024/05/14
    ジャーナル オープンアクセス 早期公開

    The solidification microstructure of Ni-hard type cast iron was investigated to evaluate the influence of Mo and W additions on the formation of carbides and graphite. The specimen was prepared based on the composition of Fe-3.3%C-0.8%Si-0.8%Mn-4.4%Ni in mass%, and Mo or W was added to the reference specimen to a maximum of 6.7%Mo or 2.9%W, respectively. Each alloy was cast into a permanent mold for the microstructural analysis. The solidification process of each alloy was also investigated by thermal analysis and quenching experiments. According to EDS and XRD analyses, it is revealed that the solidification microstructure of standard Ni-hard type cast iron consists of primary γ, γ+M3C eutectic structure and graphite, and the addition of Mo and W provides γ+M2C eutectic structure. The further addition of Mo and W increases the amount of γ+M2C eutectic structure and decreases the amount of γ+M3C eutectic structure, whereas it has little effect on the amount of primary γ. The quenching experiment reveals the graphite formation as eutectic structure between the formations of γ+M2C eutectic structure and γ+M3C eutectic structures. The addition of Mo reduces the amount of graphite, while addiction of W increases the amount of graphite. The influence of each alloying element on graphite formation could be estimated by carbon solubility and the composition of the residual liquid.

  • 小峯 慎介, 中垣内 達也, 金子 真次郎, 田路 勇樹, 堺谷 智宏, 佐藤 健太郎
    原稿種別: 論文
    論文ID: TETSU-2024-035
    発行日: 2024年
    [早期公開] 公開日: 2024/05/14
    ジャーナル オープンアクセス 早期公開

    A fundamental study on the axial crush performances of HSS (High Strength Steel) was carried out to clarify the effects of microstructure and mechanical properties on crashworthiness. Axial crush tests were performed to evaluate the crush performances of the HSS with different microstructures and mechanical properties and identify the fracture origins. The cracks in the press formed area were observed and the cracks led to the fractures. The high λ (Hole expansion ratio) steel showed excellent crush performances by crack suppression. Crash deformation in the press formed area was simulated by the ORB (Orthogonally Reverse Bending) fracture tests and the crack suppression factors were investigated. Through the ORB fracture test, it was clarified that the reduction of the hardness gaps between phases and the refinement of the hard phases (Fresh martensite) were effective for suppressing cracks in the press formed area. These microstructures were occurred by the Q&P (Quenching & Partitioning) process for increasing λ. Therefore, it was found that the microstructural design for increasing λ also contributed to excellent crush performances.

  • 安住 和久, 坂入 正敏, 伏見 公志, 佐藤 京, 三上 健, 三浦 正純
    原稿種別: 論文
    論文ID: TETSU-2024-007
    発行日: 2024年
    [早期公開] 公開日: 2024/05/08
    ジャーナル フリー 早期公開

    Daily and seasonal changes in temperature (T) and relative humidity (RH) were monitored using a sensor network system installed in the Hokkaido Centennial Memorial Tower, built more than 50 years ago using weathering steel, to investigate its corrosion condition. Five T-RH sensors were set at the south side wall, inside the south tower, in the semi-open central area, inside the north tower, and on the north side wall on the 4th, 14th, and 24th floors. The T changed as a function of altitude, location in the floor, season, weather, solar radiation, diurnal cycle, distance from the wall, etc. The highest T of the south wall at daytime in the winter season could rise more than 30 °C even if the outer temperature was below 0 °C due to solar radiation causing the repetition of ice or snow melting in the daytime and freezing of water at night. The change in RH and T inside the tower followed a Tomashov-type RH-T curve (high RH at low T in the morning and evening). In winter, however, T and RH distribution, i.e., high-RH (> ca.60%) area below the freezing point and low-RH area with the high-T, caused air transportation inside the tower, condensation (and freezing) in the low-T area, and drying in the high-T area. In the visual inspections, severe corrosion, such as blistering and peeling, has been observed at the bottom of the tower, where snow has accumulated, and rainwater has stayed for a long time, especially at welds and joints.

  • 鈴木 茂, 佐藤 成男, 今宿 晋, 佐藤 裕之, 田中 俊一郎
    原稿種別: レビュー
    論文ID: TETSU-2024-016
    発行日: 2024年
    [早期公開] 公開日: 2024/05/08
    ジャーナル オープンアクセス 早期公開

    This article describes results of the residual stress measurements in different iron alloys using a few non-destructive techniques based on X-ray diffraction. It was shown that the results provide useful information for understanding the microstructural phenomenon in each alloy, although these techniques are not universally applicable to various cases. In this paper, the residual stresses formed during stress-induced martensitic transformation and its reverse transformation in shape memory alloys, the residual stresses balancing between two phases in duplex stainless steels and the residual stresses formed by inhomogeneous plastic strains in polycrystalline twin-induced plasticity steels are shown. It is important to select an adequate method according to the phenomena and properties of interest in iron alloys. The residual stresses formed in a high-entropy alloy containing iron are also presented, taking into account into the inhomogeneity in bulk. The residual stresses and related microstructural data in materials in structures and device components are considered to be effective parameters for evaluating their mechanical properties. While modern diffraction measurement methods are relatively easy to be operated, it is noted that the results include issues related to the microstructure of the materials. These issues should also be discussed in the residual stress measurements at different scales, and reliable fundamental data related to residual stress considering the microstructure would be necessary for discussion.

  • 渡辺 将仁, 浦川 潔, 石垣 芳夫, 古瀬 泰輔, 粕谷 素洋, 佐藤 成男, 鈴木 茂
    原稿種別: 論文
    論文ID: TETSU-2024-026
    発行日: 2024年
    [早期公開] 公開日: 2024/05/01
    ジャーナル オープンアクセス 早期公開

    To understand the anisotropy of properties in FeCo-V alloy sheets, the Young's modulus, texture, and residual stress of samples of different treatments were investigated using the X-ray diffraction method. In the cold-rolled alloy sheets, the anisotropy of Young's modulus in different directions within the sheet plane was similar to that of the annealed samples at 600 °C, although there was some variation. The anisotropy of the Young's modulus was different from that of the cold-rolled and annealed samples at low temperatures. According to the results of texture measurements on alloy sheets subjected to each treatment, the direction of the lower Young's modulus almost corresponds to a specific texture component, suggesting that the texture component affects the anisotropy of the Young's modulus. X-ray diffraction rings from alloy sheets are used in the residual stress measurement, which may contain information on the process of alloy sheets and changes in the texture due to heat treatment. Residual stress shows anisotropy within the surface of cold-rolled alloy sheets, indicating high compressive residual stress in the rolling direction and in the transverse direction. In general, lower residual stress in the sheets annealed at 600 °C may be related to dislocation rearrangement in the alloys. Furthermore, in the samples annealed at 850 °C, recrystallization and related phenomena are reflected in the deviation from the plot for residual stress, which may also affect the texture.

  • 深谷 宏, Jonah Gamutan, 久保 真, 矢野 慎太郎, 鈴木 茂, 三木 貴博
    原稿種別: 論文
    論文ID: TETSU-2024-018
    発行日: 2024年
    [早期公開] 公開日: 2024/04/25
    ジャーナル オープンアクセス 早期公開

    Controlling the size, number, and composition of secondary inclusions is vital in the production of high-quality steels. In this study, experimental and computational investigation of the relationship between secondary inclusion formation in Fe-36mass%Ni alloy and cooling rate was carried out. Assuming the case of large ingots, solidification experiments using various cooling rates (0.17 to 128 K/min) were employed and the size, number, composition, and distribution of inclusions were analyzed by SEM-EDS automatic inclusion analysis. Like previous studies, inclusion number density increased with increasing cooling rate, while inclusion size decreased with increase of cooling rate. On the contrary, oxide inclusion area fraction was found to have little relationship with the cooling rate and was instead found related with oxygen content of the sample. As a new attempt to investigate the relationship between microsegregation and secondary inclusion formation, a combination of SEM-EDS analysis and EPMA mapping analysis was carried out. By superimposing information of microsegregation and inclusions, it was found that high-Al2O3 inclusions formed during the early stage of solidification, whereas low-Al2O3 inclusions formed during the later stage of solidification. These findings suggest that Al2O3 inclusions formed in the early stage of solidification reacted with the remaining Si-enriched liquid steel and changed into low-Al2O3 inclusions. Experimental results were also confirmed by thermodynamic calculations. Present work made it possible to understand deeper the relationship between microsegregation and secondary inclusion formation.

  • 渡邉 啓介, 西川 元裕, 中崎 盛彦, 松本 良, 宇都宮 裕
    原稿種別: 論文
    論文ID: TETSU-2024-030
    発行日: 2024年
    [早期公開] 公開日: 2024/04/25
    ジャーナル オープンアクセス 早期公開

    To improve the prediction accuracy of oil quenching distortion, the transformation plasticity coefficient was determined by oil quenching experiment on the steel sheet and numerical simulations. The cooling curve of the steel sheet during oil quenching and the deflection after quenching were measured under three experimental conditions. In the first condition, austenitic stainless steel sheet was quenched into cold quenching oil for confirmation of the validation of the temperature prediction results by the numerical simulation. In the second condition, chromium molybdenum steel sheet was quenched into cold quenching oil for confirmation of the validation of the latent heat predicted by the numerical simulation. By fitting the results of the numerical simulation to the deflection of the sheet in this experiment, the transformation plasticity coefficient in the martensitic transformation of the chromium molybdenum steel was determined to be 21 x 10-5 MPa-1. In the third condition, chromium molybdenum steel sheet was quenched into semi-hot quenching oil to verify the accuracy of the prediction of heat treatment distortion using the determined transformation plasticity coefficient. The error in the deflection of the sheet after oil quenching using the determined transformation plasticity coefficient was reduced to 6% from 64% (the previous report). The accuracy of distortion prediction was improved by changing the specimen morphology used in oil quenching experiments from bars to sheets.

  • 林田 将汰, 光延 卓哉, 竹林 浩史
    原稿種別: 論文
    論文ID: TETSU-2024-013
    発行日: 2024年
    [早期公開] 公開日: 2024/04/20
    ジャーナル オープンアクセス 早期公開

    During hot stamping, Zn oxidation occurs on the surfaces of Zn-coated steel sheets such as galvanized iron and galvannealed sheets. In order to elucidate the effect of Al in the Zn coating layer on the Zn oxidation, the present study investigated the amount of ZnO formed on the Zn-coated steel sheets with and without Al addition to the coating layer. The amount of ZnO was found to decrease upon Al addition. The microstructural analysis of the Zn-coated steel sheets with Al addition revealed that the added Al became the ZnAl2O4 layer at the interface between the ZnO layer and Zn coating layer after hot stamping. As a result, Zn oxidation is considered to be suppressed by the presence of the ZnAl2O4 layer.

  • 德田 公平, 後藤 靖人, 齊藤 完, 竹林 浩史, 植田 浩平
    原稿種別: 論文
    論文ID: TETSU-2024-024
    発行日: 2024年
    [早期公開] 公開日: 2024/04/19
    ジャーナル オープンアクセス 早期公開

    The purpose of this report is to compare the coating structure and corrosion mechanism of newly developed Zn-19%Al-6Mg-Si with conventional Zn-Al-Mg alloy coating Zn-11%Al-3%Mg-0.2%Si. In past papers the corrosion resistance of Zn-Al-Mg alloy coating layers was mainly discussed based on analysis methods that focus on one aspect of early corrosion stage. However, this report focuses on the changes in the corrosion mechanism until the end of the coating lifespan and picks up the factors of the coating layer that contribute to corrosion resistance.

    The results of the corrosion cross section images of the Zn-Al-Mg alloy coating layer after cyclic corrosion test suggested that corrosion of the coating layer progresses selectively in each phase, which means each phase has its own electrochemical potential. Considering the differences in the corrosion mechanisms of these two coated steel sheets, it was suggested that the phase proportion of the coating layer and the unique potential determine the corrosion resistance of the coating layer.

  • 柴尾 史生, 莊司 浩雅, 中野 博昭
    原稿種別: 論文
    論文ID: TETSU-2024-038
    発行日: 2024年
    [早期公開] 公開日: 2024/04/19
    ジャーナル オープンアクセス 早期公開

    Vanadium composite electrogalvanized (Zn-V hydroxide) steel sheets were prepared by electroplating using a horizontal flow cell. The structure of Zn-V plating layer depended on the flow rate of electrolyte and the current density, and the performance of Zn-V steel sheets depended on the structure of plating films. The Zn-V plating films composed of two-phase structure without cracks showed the high corrosion resistance and high adhesion. The two-phase layer consisted of the field oriented fiber and non-field oriented texture. The field oriented fiber phase was mainly composed of metallic Zn, and the non-field oriented phase was mainly formed from the amorphous V compound. The V compound in the non-field oriented phase seems to be formed by the hydrolysis reaction of V ions due to pH increase in cathode layer according to hydrogen evolution during Zn-V plating. The Zn-V steel sheets had a black and low-gloss appearance compared to the conventional electrogalvanized steel sheet (EG). Since the V compound in the non-field oriented texture was black and the field oriented texture formed the surface roughness, the lightness and gloss of the Zn-V steel sheets decreased with increasing V content in plating films.

  • 矢埜 泰武, 加藤 裕介, 細原 聖司, 宮崎 健太, 椋木 俊文
    原稿種別: 論文
    論文ID: TETSU-2024-012
    発行日: 2024年
    [早期公開] 公開日: 2024/04/17
    ジャーナル オープンアクセス 早期公開

    Main application of steelmaking slag is a base course material. In order to utilize slag as a base course material, it is necessary to have various characteristics in the criteria, and the modified California Bearing Ratio (CBR) value which evaluates the performance as a base course material is an important index in comparison with other competitors. Although it is expected that various factors such as properties and granularity affect CBR characteristics and compaction properties, the particle properties and granularity of steelmaking slag is different on each refining process which produce steelmaking slag. In addition, until now, X-ray CT measurement for slag base course material and effect of particle property have not been examined. Therefore, in this study, measurement of the internal phenomena of the steelmaking slag base course material by micro-focused X-ray CT and various measurement were carried out. It was revealed that the particle strength of porous particles is lower than that of dense real particles regardless of particle size and the subbase bearing capacity did not differ as much as the particle strength difference. In addition, from the mechanism by which the stress propagates and elastic finite element analysis by using X-ray CT, it was considered that the distribution of the stress was changed by the dispersion of the particle strength of each grain, and it affected the property of base course material which was the integral value of the effective stress.

  • 王 飛躍, 島崎 航平, 胡 少鵬, 石井 抱, 梅垣 嘉之, 伊藤 友彦
    原稿種別: 論文
    論文ID: TETSU-2024-021
    発行日: 2024年
    [早期公開] 公開日: 2024/04/16
    ジャーナル オープンアクセス 早期公開

    In this study, we develop a high-speed, high-resolution vision system that enables real-time measurement of deflection displacement distribution in cranes with long beam structures. It can measure dynamic displacement distribution with sub-pixel accuracy in real time by executing digital image correlation for 4096×904 images at 100fps. Millimeter-level deflections at tens of points on a crane are measurable with the position of its moving load when a camera is tens of meters away from the crane. The trolly of a crane indicates the load position, and our system can also analyze deflection influence lines at all points on the crane as speed-invariant features that indicate its structural property. The effectiveness of our vision-based displacement measurement is demonstrated by showing experimental results for (1) a 1-m-length belt conveyor, and (2) an unloader crane with a 98-m beam structure operating in ironworks.

  • 大野 紘明, 楯 真沙美, 大重 貴彦, 飯塚 幸理
    原稿種別: 論文
    論文ID: TETSU-2024-009
    発行日: 2024年
    [早期公開] 公開日: 2024/04/13
    ジャーナル オープンアクセス 早期公開

    Surface inspection of steel products is very important for quality assurance. Many automatic in-line surface inspection systems using the camera technique have already been installed in sheet production lines. However, automatic surface inspection of steel products such as steel pipes and thick plates has not advanced because the entire product surface is covered with uneven mill scale, and it is difficult to distinguish the pattern of the mill scale from defects with concave-convex shapes in images of the camera.

    The authors developed a new surface inspection system using the twin illumination and subtraction technique, which emphasizes only concave-convex defects while canceling the pattern of the mill scale covering these types of steel products. An optical approach to enhance the detection performance of this system was already reported in connection with the development of a steel plate surface inspection technology. This paper discusses the development of a new image processing technique to detect defects from obtained images in order to satisfy the conditions of introducing automatic inspection systems at steel production lines. Concretely, a high-speed bright-dark pattern detection algorithm using expansion and conjunction processing was developed, and improved the processing speed by 22.6 times relative to the conventional simple method. An effective new original feature, overlap ratio of bright parts, was also developed, resulting in a 5.15 % improvement in the classifier concordance rate relative to that without the proposed features. The developments described above have realized automatic surface inspection systems suitable for introduction in steel production manufacturing processes.

  • 小森 和武
    原稿種別: レビュー
    論文ID: TETSU-2024-033
    発行日: 2024年
    [早期公開] 公開日: 2024/04/13
    ジャーナル オープンアクセス 早期公開

    This paper reviews studies on the prediction of ductile fracture during metal forming using an ellipsoidal void model and some other models proposed by the author and some relevant studies. Section 2 discusses the research on the theory of voids for predicting ductile fracture during metal forming. Section 3 summarizes the simulation method for predicting ductile fracture during metal forming using the ellipsoidal void model, and Section 4 summarizes the simulation result on the ductile fracture prediction during metal forming using the ellipsoidal void model. Section 5 shows the applicability of the ellipsoidal void model and the simulation result on the ductile fracture prediction during metal forming using some other models.

  • 砂子 真魅, 水本 政隆, 大井 梓, 多田 英司
    原稿種別: 論文
    論文ID: TETSU-2024-036
    発行日: 2024年
    [早期公開] 公開日: 2024/04/13
    ジャーナル オープンアクセス 早期公開

    Automotive suspension springs are required to be high-strength and lightweight, and currently have a maximum strength of 2000 MPa. In addition, they must have high resistance to hydrogen embrittlement in the service environment. From previous researches, Si addition or rapid tempering improve the hydrogen embrittlement resistance of low alloy steel. In this study, we investigated the hydrogen embrittlement properties of steel samples with different Si contents and tempering rates and the effects of the fine iron carbides and retained austenite on its properties for 2000 MPa suspension spring steel. JISSUP7 (2.0Si) and SAE9254 (1.4Si) spring steels were tempered at different tempering rates by induction (IH) and furnace heating (FH) methods. Four-point bending tests under corrosion cycles were performed on these steels, and the time to failure was measured. The results show that the 2.0Si-IH steel with higher Si content and higher tempering rate has the longest fracture life and highest resistance to hydrogen embrittlement, even with relatively high diffusible hydrogen content. The size and volume fraction of iron carbides and retained austenite were evaluated by TEM, EBSD, and synchrotron XRD, and the 2.0Si-IH steels were found to have the smallest size and the highest volume fraction of fine iron carbides Fe2-3C(e) and the highest amount of retained austenite. It is considered that the fine iron carbides of Fe2-3C(e) work as hydrogen trap sites and that their high dispersion suppresses dislocation movement. They suppress hydrogen accumulation in stress concentrated areas and are expected to improve resistance to hydrogen embrittlement.

  • 山本 孝, 宮本 一範
    原稿種別: 論文
    論文ID: TETSU-2024-015
    発行日: 2024年
    [早期公開] 公開日: 2024/04/11
    ジャーナル オープンアクセス 早期公開

    Pt L3 edge XANES spectra of various kinds of platinum compounds were recorded using a laboratory-type X-ray absorption spectrometer. In order to investigate precision and the accuracy for oxidation state analysis of platinum species with a simple method, the white line intensity was evaluated by least squares fitting using four kinds of profile functions (Gaussian, Lorentzian and two types of pseudo-Voigt functions) and one arctangent function for continuum state. Differences in estimated values and the deviations depending on the type of profile function adopted were discussed. White line intensity could be determined easily and reproducibly using pseudo-Voigt function where a fraction of Lorentzian function is variable. The relationship between oxidation number of Pt compounds and white line area obtained by pseudo-Voigt method are the most preferable. The height of the white line for divalent compounds varies greatly in some cases, and then it is inappropriate to apply the height to estimation of the oxidation number of unknown samples. The changes in platinum species of silica supported Pt(NH3)4Cl2 of a catalyst precursor during air calcination was examined by in-situ XANES. The platinum species exist as divalent species up to 473 K, and changed to zero-valent between 473 and 573 K. The present in-situ laboratory XAFS experiment and the oxidation state analysis is consistent with SR XAFS studies by other research group.

  • 河合 潤, 加藤 駿英, 今宿 晋
    原稿種別: 技術報告
    論文ID: TETSU-2024-025
    発行日: 2024年
    [早期公開] 公開日: 2024/04/11
    ジャーナル オープンアクセス 早期公開

    X-ray spectra scattered to 90°were measured for various scatterers of 5-mm thick B4C, acrylic, titanium, iron, zirconium, and lead plates, and their combinations such as B4C(5 mm thick) on acrylic plate (1 or 5 mm thick). The degree of polarization was estimated from the observed X-ray spectra at 0°and 90°. Using the best scatterer as an X-ray polarizer for each samples, polarization X-ray fluorescence (XRF) spectra of various samples such as cabtyre cable, book cover made of synthetic-resin, and steel making slag, compared with non-polarization XRF spectra. Toxic elements in some samples were more sensitive for polarized XRF, while other samples were more sensitive for non-polarized XRF. The reasons for such contradicted experimental results were discussed. Most of the measurements were performed by 15 mW X-ray tube power for polarization XRF, and by 3 mW for non-polarized XRF. The meanings of lowest power XRF measurements in the literature were also discussed. This kind of low power experiments may open the possibility of easy way of experiments, and non-invasive XRF analysis for cultural heritage.

  • 福本 倫久, 高橋 弘樹
    原稿種別: 論文
    論文ID: TETSU-2024-022
    発行日: 2024年
    [早期公開] 公開日: 2024/04/10
    ジャーナル オープンアクセス 早期公開

    The environmental resistance of pure iron was evaluated with oxygen and hydrogen sensor installed after the oxidation furnace. The amount of introduced oxygen was precisely controlled by oxygen pump-sensor at the front stage of the oxidation furnace and the reaction with hydrogen was analyzed. As a result, when oxygen was supplied, a reaction between hydrogen and oxygen occurred, but when sufficient oxygen was not supplied, a hydrogen-vapor environment was created and oxidation was not accelerated. However, when the amount of supplied oxygen was excessive, the environment became oxygen-steam environment and the oxidation was accelerated. At that time, it was clarified that the oxidation by oxygen was dominant under the oxygen-water vapor environment, and the mass gain increased. In addition, the border of the region dominated by oxygen oxidation and that by steam oxidation was clarified by precisely controlling the amount of supplied oxygen by the oxygen pump sensor.

  • 谷 昌幸, 木下 林太郎, 大西 一光, 池本 秀樹, 和崎 淳, 橋本 洋平, 原田 俊哉, 平田 浩, 柿本 昌平
    原稿種別: 論文
    論文ID: TETSU-2024-011
    発行日: 2024年
    [早期公開] 公開日: 2024/04/02
    ジャーナル オープンアクセス 早期公開

    High phosphate slag fertilizer (SHP) contains phosphorous, calcium, magnesium and silicon, expected to be effective in supplying plant nutrients and improving soil acidity. We clarified the characteristics and effects of the SHP as a fertilizer. Nippon Steel Corporation prepared the SHP prototypes by concentrating phosphorus through high-temperature processing. Five types (SHP12, SHP15, SHP18-1, SHP18-2, SHP27-2) were examined through dissolution test, pot cultivation experiment, and evaluation of improving effect on soil acidity. The SHP12 was insoluble in water but soluble in various acids and most SHP contained more than 95% of acid-soluble phosphate and silicate. Above-ground growth and phosphate uptake of spinach was higher in the SHP12 plot than in no-phosphate, ammonium phosphate and fused phosphate plots, indicating that phosphorus in the SHP12 could be absorbed more easily than the common phosphate fertilizers. Above-ground growth and phosphate uptake of wheat was also high in the SHP12 and SHP15 plots, which was comparable to ammonium phosphate plot. However, the SHP27-2 had little effect as a phosphate fertilizer. The SHP12 and SHP15 could be expected to supply calcium and silicon as well as phosphorous. Although most SHP showed the same ability to improve soil acidity as calcium carbonate, it might be necessary to avoid excessive increase in soil pH depending on the soil condition and the ability of SHP. We can conclude that if the composition of the SHP is optimized, it can be used as a fertilizer with multiple effects depending on soil types, nutrient status, and crop types.

  • 浦中 祥平, 高梨 美咲, 前田 拓也, 増村 拓朗, 土山 聡宏, 川本 雄三, 白幡 浩幸, 小林 由起子, 植森 龍治
    原稿種別: 論文
    論文ID: TETSU-2024-029
    発行日: 2024年
    [早期公開] 公開日: 2024/04/02
    ジャーナル オープンアクセス 早期公開

    The effects of retained austenite upon softening during low-temperature tempering at 373 K were investigated using martensitic carbon steels with and without retained austenite. To increase the amount of retained austenite, 10 mass% Ni was added to the base carbon steel (Fe-0.3C alloy). During tempering, the hardness decreased more rapidly in the Ni-added steel containing 6 vol.% retained austenite than in the base steel without retained austenite. Analyses of the microstructure and the carbon content in the solid solution (i.e., the solute carbon concentration) revealed that the retained austenite tended to suppress carbide precipitation and significantly reduced the solute carbon concentration in the martensitic matrix. We demonstrated that retained austenite acts as an effective absorption site for solute carbon in the martensitic matrix; however, the partitioned carbon is unevenly localized near the martensite/austenite interface, owing to the poor diffusivity at 373 K.

  • 藤﨑 大地, 林 重成, 米田 鈴枝
    原稿種別: 論文
    論文ID: TETSU-2024-006
    発行日: 2024年
    [早期公開] 公開日: 2024/03/23
    ジャーナル オープンアクセス 早期公開

    The effect of C content in steels on the formation of an Al-containing carbide layer by an Al pack method at 980℃ was investigated. The continuous layer consisting of an outer β-FeAl and inner Fe3AlC layers was formed on Fe-1.2C (in wt.%) by a short process time. An α-Fe(Al) layer with Fe3AlC precipitates was formed below the β-FeAl layer on Fe-0.7C after 16 h of process, thereafter an Fe3AlC layer was formed between the β-FeAl and α-Fe(Al) + Fe3AlC layers after 25 h. The β-FeAl and α-Fe(Al)+ Fe3AlC layers were formed on Fe-0.1C, but a continuous Fe3AlC layer was not developed after longer treatment. A continuous Fe3AlC layer formed by an Al pack method was explained by carbon enrichment at the α-Fe(Al)/γ-Fe(C) interface due to an inward growth of the α-Fe(Al) layer.

  • 奥村 諒人, 安達 勇人, 近藤 泰光
    原稿種別: 論文
    論文ID: TETSU-2023-115
    発行日: 2024年
    [早期公開] 公開日: 2024/02/22
    ジャーナル オープンアクセス 早期公開

    Blistering occurs when oxide scale swells during oxidation at steel high temperatures.Blistered scale causes surface defects when steels are rolled. An assumption has been proposed that the pressure of CO and CO2 gas generation beneath the scale causes blisters. This study the qualitative measurements of the gas pressure beneath the oxide scale were tried.A stainless tube was set in order to connect to the beneath the scale during oxidation.Positive pressures were confirmed beneath oxide scale. Also gas permeability through FeO mono-layer scale was obtained.

  • 宮崎 里穂子, 及川 紘生, 国村 伸祐
    原稿種別: 論文
    論文ID: TETSU-2023-114
    発行日: 2024年
    [早期公開] 公開日: 2024/02/06
    ジャーナル オープンアクセス 早期公開

    In this study, total reflection X-ray fluorescence (TXRF) spectra of dry residues of 10 μL, 100 µL, 200 µL, and 400 μL droplets of a solution containing 10 μg L−1 of Cr on hydrophobic film coated sample holders were measured by a portable TXRF spectrometer, and these spectra were compared. The net intensity of the Cr Kα peak per the concentration of Cr in the sample solution (counts / μg L−1) increased with an increase in the volume of a droplet of the sample solution. This was because the mass of Cr in the dry residue increased with an increase in the volume of a droplet of the sample solution. This enhancement in the net intensity of the Cr Kα peak per the concentration of Cr led to a significant improvement in the detection limit expressed as the concentration of Cr. Detection limits for Cr obtained from the measurements of the dry residues of 10 μL, 100 µL, 200 µL, and 400 μL droplets of the sample solution were 2.1 μg L−1, 0.30 μg L−1, 0.13 μg L−1, and 0.09 μg L−1, respectively. Measuring the dry residue of a large volume droplet of a water sample would be useful for the analysis of trace elements in the sample.

  • 今宿 晋
    原稿種別: 論文
    論文ID: TETSU-2023-100
    発行日: 2023年
    [早期公開] 公開日: 2023/12/14
    ジャーナル オープンアクセス 早期公開

    Identifying a crystal structure of alumina (Al2O3) scale is critical for evaluating the performance of heat-resistant alloys because α-Al2O3 is stable and protective against high-temperature oxidation and corrosion but θ- and g-Al2O3 provide poor oxidation resistance. Conventional methods to identify crystal structures of Al2O3 scales are time-consuming. Herein, the author proposes a method to rapidly identify crystal structures of Al2O3 scales on β-NiAl by obtaining their cathodoluminescence (CL) spectra. α-, θ-, and g-Al2O3 can be identified by detecting a sharp peak at 695.8 nm and 686.3 nm, and a broad peak at around 700 nm, respectively, in CL spectra. Concentrations of α-, θ-, and g-Al2O3 scales can be determined roughly from intensities of these peaks. This method can be applied to areas ranging from the millimeter to micrometer scale, and the acquisition time for the CL spectra was less than 10 s. The results indicate that obtaining CL spectra contributes to the identification of crystal structures of Al2O3 scales on heat-resistant alloys and a reduction in time to evaluate the performance of heat-resistant alloys.

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