Creep Behavior and Degradation of Subgrain Structures Pinned by Nanoscale Precipitates in Strength-Enhanced 5 to 12 Pct Cr Ferritic Steels

被引:90
作者
Armaki, Hassan Ghassemi [1 ]
Chen, Ruiping [1 ]
Maruyama, Kouichi [1 ]
Igarashi, Masaaki [2 ]
机构
[1] Tohoku Univ, Grad Sch Environm Studies, Sendai, Miyagi 9808579, Japan
[2] Sumitomo Met Ind Ltd, Corp Res & Dev Labs, Amagazaki 6600891, Japan
来源
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE | 2011年 / 42A卷 / 10期
关键词
LONG-TERM CREEP; MARTENSITIC 9CR STEELS; POWER-PLANT STEELS; Z-PHASE; MICROSTRUCTURAL ASPECTS; MULTIREGION ANALYSIS; MOD.9CR-1MO STEEL; RUPTURE LIFE; DEFORMATION; TEMPERATURE;
D O I
10.1007/s11661-011-0726-8
中图分类号
T [工业技术];
学科分类号
08 ;
摘要
Creep behavior and degradation of subgrain structures and precipitates of Gr. 122 type xCr-2W-0.4Mo-1Cu-VNb (x = 5, 7, 9, 10.5, and 12 pct) steels were evaluated during short-term and long-term static aging and creep with regard to the Cr content of steel. Creep rupture life increased from 5 to 12 pct Cr in the short-term creep region, whereas in the long-term creep region, it increased up to 9 pct Cr and then decreased with the addition of Cr from 9 to 12 pct. Behavior of creep rupture life was attributed to the size of elongated subgrains. In the short-term creep region, subgrain size decreased from 5 to 12 pct Cr, corresponding to the longer creep strength. However, in the long-term creep region after 10(4) hours, subgrain size increased up to 9 pct Cr and then decreased from 9 to 12 pct, corresponding to the behavior of creep rupture life. M23C6 and MX precipitates had the highest number fraction among all of the precipitates present in the studied steels. Cr concentration dependence of spacing of M23C6 and MX precipitates exhibited a V-like shape during short-term as well as long-term aging at 923 K (650 A degrees C), and the minimum spacing of precipitates belonged to 9 pct Cr steel, corresponding to the lowest recovery speed of subgrain structures. In the short-term creep region, subgrain coarsening during creep was controlled by strain and proceeded slower with the addition of Cr, whereas in long-term creep region, subgrain coarsening was controlled by the stability of precipitates rather than due to the creep plastic deformation and took place faster from 9 to 12 pct and 9 to 5 pct Cr. However, M23C6 precipitates played a more important role than MX precipitates in the control of subgrain coarsening, and there was a closer correlation between spacing of M23C6 precipitates and subgrain size during static aging and long-term creep region.
引用
收藏
页码:3084 / 3094
页数:11
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