21/4Cr-1Mo鋼管材の高温クリープ特性について

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概要

• 論文の詳細を見る

• It is a well-known fact that ferritic steels are practically more useful than austenitic steels as tube materials, and it requires on the part of the users in general to raise as much as possible the creep resisting temperature of ferritic steels. However, 2 1/4 Cr-1 Mo steel has been so far the highest class of materials of ferritic steel in practical use, obtainable in market and used most frequently. On the other hand, still higher class materials, such as 7 Cr- 1 Mo or 9 Cr-1 Mo steel, have been under researches and have been developed but they have not yet attained the stage for practical use. In the super heater tubes for boiler with a steam temperature of 570℃, austenitic steels are used in general, because, when the metal temperatures of the tubes exceed 600℃, the strength of Cr-Mo steels should become insufficient. However, with the advancement of the development of ferritic steels, there is the possibility of either 7 Cr-1 Mo or 9 Cr-1 Mo steel coming into practical use up to the metal temperature of 570〜620℃. In the case of the temperature exceeding 600℃, 18-8 Ti steel used for supperheater tubes in America but some cases of accidents have been reported on account of the expansion and destruction of tubes while in use. Causes of these accidents are due to such special properties of austenitic steels as difficulty to control grain growth and embrittlement of grain boundaries by precipitation of carbides. Those events could be prevented if there appear ferritic steels which can be used in practise in the temperature range of 570〜620℃. In that sense it is desirable that ferritic steels with higher heat resistance be developed, and as the first step of such development, it is necessary to ascertain the maximum heat resisting temperatures of 2 1/4 Cr-1 Mo steel tubes, which are always determined according to the ASME or JIS Boiler Construction Code. However, these code values are estimated from the creep data of comparatively short-time and we understand that so far there have been no researches for determining the adaptability of code values to the steels on sale from the results of long-time creep data.

• 社団法人日本材料学会の論文
• 1961-03-15

著者

• 前田 徳美

  川崎重工業(株)技術研究所

関連論文

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• 耐熱鋼のクリープ破断強度の熱力学的評価と長時間強度の外挿
• 組織変化を考慮したオーステナイト鋼の長時間クリープラプチャー強度の推定
• 21/4Cr-1Mo鋼管材の高温クリープ特性について
• スチームタービン用ローター材に関する二,三の考察

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