TY - JOUR
T1 - Cr concentration dependence of overestimation of long term creep life in strength enhanced high Cr ferritic steels
AU - Maruyama, K.
AU - Ghassemi Armaki, H.
AU - Chen, R. P.
AU - Yoshimi, K.
AU - Yoshizawa, M.
AU - Igarashi, M.
N1 - Funding Information:
This study is a part of research activities on “Fundamental Studies on Technologies for Steel Materials with Enhanced Strength and Functions” carried out by Consortium of The Japan Research and Development Center of Metals (JRCM). Financial support from New Energy and Industrial Technology Development Organization (NEDO) is gratefully acknowledged.
PY - 2010/6
Y1 - 2010/6
N2 - Creep rupture data and microstructural degradation during aging of high Cr ferritic boiler steels with enhanced creep strength have been studied with special attention to prediction of long term creep rupture life. Tempered lath martensite structure in the high Cr ferritic steels remains unchanged during short term aging, whereas static recovery of the lath martensite structure proceeds when diffusion distance during aging becomes sufficiently long as is the case in long term creep. The static recovery brings about premature failure in long term creep and decreases in apparent activation energy for creep life. The decrease in activation energy is responsible for overestimation of rupture life reported in strength enhanced high Cr ferritic steels. The boundary from a short term region with high activation energy QH to a long term region with low activation energy QL moves towards longer time with decreasing Cr concentration. The difference in activation energy (QH - QL) primarily determines the extent of overestimation of rupture life predicted from short term data. In general, the extent of overestimation is less serious at 9%Cr as compared to 12%Cr.
AB - Creep rupture data and microstructural degradation during aging of high Cr ferritic boiler steels with enhanced creep strength have been studied with special attention to prediction of long term creep rupture life. Tempered lath martensite structure in the high Cr ferritic steels remains unchanged during short term aging, whereas static recovery of the lath martensite structure proceeds when diffusion distance during aging becomes sufficiently long as is the case in long term creep. The static recovery brings about premature failure in long term creep and decreases in apparent activation energy for creep life. The decrease in activation energy is responsible for overestimation of rupture life reported in strength enhanced high Cr ferritic steels. The boundary from a short term region with high activation energy QH to a long term region with low activation energy QL moves towards longer time with decreasing Cr concentration. The difference in activation energy (QH - QL) primarily determines the extent of overestimation of rupture life predicted from short term data. In general, the extent of overestimation is less serious at 9%Cr as compared to 12%Cr.
KW - Activation energy for rupture life
KW - High Cr ferritic steel
KW - Microstructural degradation
KW - Overestimation of rupture life
KW - Tempered lath martensite
UR - http://www.scopus.com/inward/record.url?scp=77953546256&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77953546256&partnerID=8YFLogxK
U2 - 10.1016/j.ijpvp.2010.03.012
DO - 10.1016/j.ijpvp.2010.03.012
M3 - Article
AN - SCOPUS:77953546256
SN - 0308-0161
VL - 87
SP - 276
EP - 281
JO - International Journal of Pressure Vessels and Piping
JF - International Journal of Pressure Vessels and Piping
IS - 6
ER -