著者

丸山 公一 中村 純也 吉見 享祐

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.100, no.3, pp.414-420, 2014 (Released:2014-02-28)

参考文献数

22

被引用文献数

2

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Conventional time-temperature-parameter (TTP) methods often overestimate long-term creep rupture life of high Cr ferritic steels. The cause of the overestimation is examined paying attention to temperature and stress dependence of creep rupture life of Gr.91, 92 and 122 steels. In stress-rupture data of all the three steels there are four regions with different values of stress exponent n for rupture life. Activation energies Q for rupture life in the regions take at least three different values. The values of n and Q decrease in a longer-term region. The decrease in Q value is the cause of the overestimation of long-term rupture life predicted by the conventional TTP methods unable to deal with the change in Q value. Therefore, before applying a TTP analysis to stress-rupture data, the data should be divided into several data sets so that Q value is unique in each divided data set. When this multi-region analysis is adopted, all the data points of the steels can be described with higher accuracy, and their long-term rupture life can be evaluated more correctly.

著者

紙川 尚也 阿部 吉剛 宮本 吾郎 船川 義正 古原 忠

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.99, no.5, pp.352-361, 2013 (Released:2013-04-30)

参考文献数

46

被引用文献数

3 6

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Tensile behavior and structure-property relationship of ferritic steels with nano-sized carbide dispersion were invesigated using Ti-added steel and Ti,Mo-added low carbon steels. By austenitizing followed by isothermal heat treatment at 700°C, polygonal ferrites containing very fine carbides of TiC and (Ti,Mo) C were obtained in the Ti-added and the Ti,Mo-added steels, respectively. The size of such carbides was finer in the Ti,Mo-added steel than in the Ti-added steel at the same holding period of isothermal heat treatment. The results of tensile tests for these samples showed that the strength is higher as the diameter of the carbides is smaller. The structure-based strength calculation led to a good agreement with the experiments, when it was assumed that the Ashby-Orowan mechanism is dominant for precipitation strengthening of nano-sized alloy carbides. It was also suggested that a relatively large tensile ductility is related to enhanced recovery during the tensile deformation, accompanied with promotion of secondary slips or cross slips in a finer scale due to the nano-sized particles.

著者

植田 芳信 佐山 惣吾 西川 泰則 鈴木 良和 信岡 聡一郎

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.68, no.14, pp.2046-2048, 1982 (Released:2009-06-19)

被引用文献数

3

著者

水上 英夫 林 宏太郎 沼田 光裕 山中 章裕

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.97, no.9, pp.457-466, 2011-09-01 (Released:2011-09-06)

参考文献数

50

被引用文献数

1 8

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Solid–liquid interfacial energy of steel during solidification was measured predicted from the both experimental techniques of unidirectional solidification and thermal analysis applying the dendrite growth model and heterogeneous nucleation model. Solid–liquid interfacial energy changed depending on primary phase during solidification, i.e., that of primary δ phase was larger than that of γ phase. When the primary phase was the same, solid–liquid interfacial energy increased with increasing carbon content. Primary dendrite arm spacing changed depending on solid–liquid interfacial energy. A trace amount of bismuth which had the effect of a decrease in the solid–liquid interfacial energy of steel during solidification decreased primary and secondary dendrite arm spacing, significantly.

著者

小澤 純夫 月橋 文孝

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.96, no.12, pp.706-713, 2010-12-01 (Released:2010-12-25)

参考文献数

24

被引用文献数

4

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The Utility of Stock hypothesis, which assumes that an in-use stock of constructional material is a function of GDP, was formulated and a clear correlation between the world steel stock and the world GDP led to the estimation that the world demand for iron ore (primary iron) depends not on the volume of GDP but on the variation of GDP, as already reported. It also became clear that the flow of primary iron has the controlling effect on the world production of crude steel. In this study, the prediction power of the Utility of Stock hypothesis is verified. Based on the verification, the global demand for iron source until 2050 is projected by deciding a world 1-region model.

著者

小澤 純夫 林 誠一 月橋 文孝

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.95, no.6, pp.522-530, 2009-06-01 (Released:2009-08-15)

参考文献数

19

被引用文献数

4 5

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To forecast iron source demand, the Intensity of Use hypothesis, which assumes that material consumption per capita is a function of GDP per capita, is the most dominant theory in existing studies. However, this hypothesis is not effective for a world one-region model of iron sources. Therefore, we focused our attention on utility, and we suppose that economic growth is a major driver to increase the utility. As the utility of steel sustains for ages after purchase, we formulate the Utility of Stock hypothesis, which assumes that the in-use steel stock is a function of GDP. In this study, the world steel stock was computed and the Utility of Stock hypothesis was tested. Clear correlation is found between the steel stock and the GDP. It leads to the estimation that the world demand for iron ore depends not on the volume of GDP but on the variation of GDP. For the first time with total world figures, the result enables us to rationalize the recent decoupling between the world growth of iron source demand and the economic growth.

著者

小澤 純夫 月橋 文孝

出版者

一般社団法人 日本鉄鋼協会

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.95, no.10, pp.710-719, 2009-10-01 (Released:2009-12-10)

参考文献数

21

被引用文献数

7 12

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The Utility of Stock hypothesis, which assumes that the in-use stock of constructional material is a function of GDP, was formulated and the clear correlation between the world steel stock and the GDP led to the estimation that the world demand for iron ore (primary iron) depends not on the volume of GDP but on the variation of GDP, as already reported. In this study, the world steel stock in use is computed. Sensitivity analyses are conducted to show the effect of lower reliable data such as the usage period (lifetime) of iron-containing final products. Clear correlation is found between the in-use steel stock and the steel stock. Hence, the Utility of Stock hypothesis is verified.

著者

薛 佑佳 福島 康裕

出版者

The Iron and Steel Institute of Japan

雑誌

鉄と鋼 (ISSN:00211575)

巻号頁・発行日

vol.96, no.3, pp.129-137, 2010

被引用文献数

3

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To strategically discuss how steel should be produced, used and recycled, understanding of current and future flow and stock of steel is of high importance. Because steel is used in the society for many years, records in the relevant industries including import and export from the past years are crucial as well as the current up-to-date statistics when illustrating flow and stock of steel in a year. Following the pioneering national flow and stock figures developed in Japan, this paper presents Taiwanese 2006 and 2007 versions of illustration of iron and steel flow, stock, and recycling, as well as list of data sources, estimation method for missing data, prediction method for the future flow and stock and recommendation for future refinement. The methodologies were modified basing on the Japanese method, due to differences in data availability, collection methods and social background of the data. Using a bottom-up approach, stock and obsolete scrap flows are estimated for three major household appliances, <i>i.e.</i> washing machine, refrigerator, and air conditioner. From comparison of the 2006 and 2007 versions, increasing importance of scrap materials in Taiwanese crude steel production and increase of importance of external market can be seen. Increasing the number of steel products covered by bottom up approach and its combination with top-down approach is recommended, as well as the refinement of assumptions from accumulating recorded data to increase completeness of the future versions.