50～60kg/mm<SUP>2</SUP>級高張力鋼およびその溶接部の高温高圧水素による脆化

• 根本 正

  日立製作所日立研究所

• 正岡 功

  日立製作所日立研究所

• 田野崎 和夫

  日立製作所日立研究所

書誌事項

タイトル別名

• Embrittlement of 50-60 kg/mm<SUP>2</SUP> High Strength Steels and their Welded Joints by Heating in Hydrogen at High Temperatures and High Pressures

抄録

50-60 kg/mm² class four high strength steels and their welded joints were heated for various time at various temperatures 300-550°C in 200 kg/cm² hydrogen, and the changes of their mechanical properties and structures were studied at room temperaure. The process of embrittlement in longtime testing and embrittlement limits of these steeles caused by heating in hydrogen at high temperatures and high pressures were discussed.<BR>The results obtained were as follows.<BR>(1) Steels which were heated at high temperatures and high hydrogen pressures became brittle and remarkably decreased the mechanical strength and the ductility, besides both hardness and carbon content decreased, many inner cracks initiated and fissured at grain boundaries. Then this grain boundaries fissuring gave rise to deterioration of materials.<BR>(2) An addition of carbide forming elements, Mo and Cr, and the heat treatment as normalizing and tempering increase the resistanse to hydrogen attack and raise embrittlement limits.<BR>(3) The welded joints are easy to become brittle in the heat-affected zone, because of the coarse grain size, therefore they decrease more severely the resistanse to hydrogen attack than the base steels.<BR>(4) At a constant temperature and pressure, it requires an incubation time (t) to become brittle and a plot of In t vs. reciprocal of heating absolute tempereture holds a straight line relationship.<BR>(5) According to this straight line relationship, it is possible to extrapolate a critical temperature of embrittlement limits at a long time about each meterial.<BR>(6) The activation energies of embrittlement on the kinetics of hydrogen attack were calculated, but they were fairely larger than each activation energy for diffusion of hydrogen and carbon through iron. Therefore, the process of hydrogen attack will not be the hydrogen and carbon diffusion-controlled behavior. Also, it is considered that the embrittlement process is related to the temperature dependence of the movement of dislocations and vacancies in the prepicitation and crack growth process of the methane gas in carbide-hydrogen reactions. But it will be necessary to make more detailed experiments to explain the mechanism of it.

収録刊行物

• 溶接学会誌

  溶接学会誌 34 (8), 773-784, 1965

  一般社団法人 溶接学会

キーワード

• Metals and Alloys
• Surfaces, Coatings and Films
• Mechanical Engineering
• Mechanics of Materials

詳細情報

• CRID: 1390001206502827136
• NII論文ID: 130003762962
• DOI: 10.2207/qjjws1943.34.773
• ISSN: 18837204
• ISSN: 00214787
• 本文言語コード: ja
• データソース種別:
  • JaLC
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可