کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
5455997 1514647 2017 32 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Causes of heat-to-heat variation of creep strength in grade 91 steel
ترجمه فارسی عنوان
علل تغییرات گرما به گرمای مقاومت خزش در فولاد 91 درجه
کلمات کلیدی
درجه فولاد 91، قدرت خزش ساز و کار تقویت، اثر دانه ای، ارزیابی زندگی خزش مدل سازی چند منطقه ای،
موضوعات مرتبط
مهندسی و علوم پایه مهندسی مواد دانش مواد (عمومی)
چکیده انگلیسی
Heat-to-heat variation of creep strength is significant in grade 91 (Gr.91) steel, but the causes of the variation have not been well understood yet. In the present paper, creep rupture data of 14 heats of Gr.91 steel were analyzed paying attention to their chemical compositions and microstructures. The longest creep rupture lives analyzed are 2×105 h at 500 and 550 °C and 105 h at 600 °C. The causes of the heat-to-heat variation are different, depending on creep test conditions. At low temperature and high stress (creep rupture life of 104 h at 500 and 550 °C), creep rupture strength increases with increase of hardness after tempering. This suggests strengthening by a fine subgrain microstructure developed during normalizing and subsequent tempering. At higher temperature and intermediate time range (104 h at 600 °C), creep rupture strength depends on Cr concentration of the heats in addition to the hardness. This finding suggests an important contribution of recovery process of the subgrain microstructures to creep strength of the steel. In long-term creep (2×105 h at 550 °C and 105 h at 600 °C) creep rupture strength primarily increases with increasing grain size of the heats. This suggests that grain boundary sliding is an important deformation mode at low strain rate because of fine grain size usual with Gr.91 steel. Specifications on Ni concentration and N%/Al% ratio are newly introduced in the type II version of Gr.91 steel. They are not effective to eliminate a heat with low creep strength.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Materials Science and Engineering: A - Volume 696, 1 June 2017, Pages 104-112
نویسندگان
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