著者

日野谷 重晴 池田 昭夫 寺崎 富久長

出版者

社団法人日本材料学会

雑誌

材料 (ISSN:05145163)

巻号頁・発行日

vol.27, no.292, pp.81-86, 1978

被引用文献数

1

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The fracture surfaces of ferritic-perlitic steel caused by hydrogen induced cracking (HIC) and sulfide stress cracking (SSC) under the wet H₂S environment were investigated by a scanning electron microscope. It was clarified that HIC and SSC were caused by hydrogen embrittlement. The cracks of HIC initiated around the nonmetallic inclusions (MnS) and they grew in a step-wise manner by connecting each other. On the other hand, the process of SSC took place as follows; the separated small cracks of HIC were connected by the cracks perpendicular to the stress axis. The fracture due to hydrogen embrittlement exhibited some characteristic fracture patterns, such as a river like pattern, flat pattern and so on. It was supposed that these fracture patterns were formed depending on the crystallographic orientation of grains. The striation type pattern was observed on the river like pattern as well as on the flat pattern. This striation type pattern seemed to correspond to the discontinuous propagation of hydrogen embrittlement cracking. In order to determine the sharp of the river like pattern, the stereo-matching technique was applied and it was found that this pattern could be classified into three types.

著者

高山 透 日野谷 重晴 石黒 三岐雄 黒澤 文夫 安原 久雄 源内 規夫 千野 淳 九津見 啓之 儀賀 義勝 助信 豊 内山 雅夫 石井 実

出版者

社団法人日本鉄鋼協会

雑誌

鐵と鋼 : 日本鐡鋼協會々誌 (ISSN:00211575)

巻号頁・発行日

vol.82, no.2, pp.147-152, 1996-02-01

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The method for isolation and determination of TiN and (Ti, Nb)(C, N) precipitated in Nb-Ti bearing steels has been investigated in the cooperative research of the Precipitate Analysis Subcommittee of Iron and Steel Analysis Committee of Iron and Steel Institute of Japan. Also, the precipitation behavior of TiN and (Ti, Nb)(C, N) in the steels has been studied. The results are summarized as follows ; (1) TiN, (Ti, Nb)(C, N) and other precipitates were extracted by potentiostatic or galvanostatic electrolysis in 10% acetylacetone-1% tetramethylammonium chloride-methanol electrolyte. (2) Only the TiN in the above mentioned precipitates was insoluble and remained by 60℃-10% bromine-methanol solution treatment. Consequently, the amount and composition of TiN and (Ti, Nb)(C, N) could be determined quantitatively by analysis of the residues extracted by using the method of (1) and the residues after this treatment. (3) The size of TiN was several micrometers, the amount of TiN did not change with heating temperatures between 1000 and 1250℃, and the atomic ratio of Ti to N was stoichiometrically one to one. (4) Total amount of Ti and Nb in the precipitates decreased with an increase in heating temperature, because the small size of (Ti, Nb)(C, N) dissolved. (5) Both lattice constant and composition changes in (Ti, Nb)(C, N) showed that Nb and C dissolved preferably into the matrix and the composition of the precipitates approached to that of TiN with an increase in heating temperature. (6) Such behavior of precipitates agreed well with rough calculation from the solubility products.