鋼のオーステナイト粒度の高温顕微鏡観察

DOI Web Site Web Site

書誌事項

タイトル別名
  • High Temperature Microscope Observations on the Austenite Grain Size of Steels
  • コウ ノ オーステナイト リュウド ノ コウオン ケンビキョウ カンサツ

この論文をさがす

抄録

In order to determine the austenite grain size of steels continuously with the high temperature microscope, the observations on the austenite grain growth of 0.2%C steels (Si-Mn killed, or Al killed) in various atmospheres were carried out. The results obtained were as follows:<BR>(1) When 0.2%C steels were heated in 3×10−5 mmHg vacuum, the austenite grains on the specimen surface were coarsened remarkably to A.S.T.M. No. 2 at 950°C, and its grain size was markedly different from that in the inner zone.<BR>(2) If these steels were heated in extremely pure argon atmosphere in the pressure range of 0.6∼1.0 atm., the austenite grains on the specimen surface persisted in a grain size of A.S.T.M. No. 8 untill about 1150°C, and then they were coarsened. Their value of grain size was nealy equal to that of inner grains of the specimen.<BR>(3) According to the electron microscopic study, it was observed that in high vacuum atmosphere the degree of oxidation on the specimen surface was less than that in argon. From this it was considered that the mechanisms for appearance of austenite grain boundaries in these atmospheres were different. Therefore we changed the atmosphere from high vacuum to argon atmosphere at 950°C and 1000°C, but we could not observe any appearance of new grains at all.<BR>(4) As regards the surface grain growth of 0.2%C steels in various atmospheres, it was observed that the lower the degree of vacuum or the higher the argon pressure, the higher became the grain coarsening temperature.<BR>(5) Remarkable grain growth which occurred at about 950°C in high vacuum within several microns in depth from the specimen surface, took place even when mechanically polished surface was removed by electrolytic polishing.<BR>(6) It is very convenient to determine the austenite grain size continuously with the high temperature microscope. So far as this study is concerned, the value of surface grain size in 0.6∼1.0 atm. argon was nearest to that of inner grain size. In the high temperature microscope observations, however, the atmosphere must be selected cautiously and careful considerations are required to discuss the inner states of the specimen according to the experimental results of the specimen surface only. It may be also said that these cautions are applicable to the determination of the austenite grain size by oxidation method.

収録刊行物

  • 日本金属学会誌

    日本金属学会誌 28 (6), 341-348, 1964

    公益社団法人 日本金属学会

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ