Intergranular Fracture of a High Purity Iron Due to Oxygen

• Matsui H.

  Research Institute for Iron, Steel and Other Metals, Tohoku University

• Kimura H.

  Research Institute for Iron, Steel and Other Metals, Tohoku University

抄録

In spite of much effort, the effect of oxygen on the intergranular fracture (IGF) of iron has not been clarified as yet. There are at least three reasons for this; (i) the specimens were not pure enough, (ii) the irons so far used showed IGF at low temperatures even without oxygen, and (iii) the solubility of oxygen in iron is not known accurately.<BR>We have prepared a high purity iron which in a form of smooth wire does not show IGF at 4.2 K by tensile test. Polycrystalline specimens of this iron was doped with oxygen; a thin oxide film was formed on the surface and a concentration (<several mass ppm) of oxygen was dissolved in equilibrium with the oxide. Thereafter, the oxide film was removed and tensile test was performed between 4.2 and 20 K. Results are as follows:-<BR>1. As the oxygen concentration is increased by increasing the doping temperature (873, 973 and 1073 K), the elongation to fracture at 4.2 K is decreased.<BR>2. Specimens, which are doped with oxygen at 973 and 1073 K and fracture along grain boundaries without any appreciable elongation, are completely ductile at 20 K.<BR>3. If well-decarburized and not doped with oxygen, a commercial high purity iron (the Johnson-Matthey iron) is more susceptible to IGF than our high purity iron.<BR>The above results show that oxygen segregated at grain boundaries weakens the grain boundary cohesion of iron to some extent, but the effect is not so large as considered before. Some previous researches have shown that smooth specimens fracture along grain boundaries by tension at 77 K. These results should be interpreted as due to oxide particles or to interactions between oxygen and other impurities, and not due solely to the oxygen segregated at grain boundaries.

収録刊行物

• Transactions of the Japan Institute of Metals

  Transactions of the Japan Institute of Metals 24 (8), 539-547, 1983

  社団法人 日本金属学会

キーワード

• intergranular fracture
• high purity iron
• grain boundary segregation of oxygen
• intrinsic strength of grain boundaries
• tensile tests
• extremely low temperature

詳細情報

• CRID: 1390001205118653696
• NII論文ID: 130003486093
• DOI: 10.2320/matertrans1960.24.539
• ISSN: 24324701
• ISSN: 00214434
• Web Site: https://www.jstage.jst.go.jp/article/matertrans1960/24/8/24_8_539/_pdf
• 本文言語コード: en
• データソース種別:
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  • CiNii Articles
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