TY - JOUR
T1 - Changes in strengthening mechanisms in creep of 9Cr-1.8W-0.5Mo-VNb steel tested over wide ranges of creep conditions
AU - Maruyama, Kouichi
AU - Sekido, Nobuaki
AU - Yoshimi, Kyosuke
N1 - Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/4
Y1 - 2021/4
N2 - The present paper studies stress, temperature and heat dependence of creep rupture life of 9Cr-1.8W-0.5Mo-VNb (Gr. 92) steel with creep rupture data of 4 heats reported in National Institute for Materials Science Creep Data Sheet 48B. In creep of Gr. 92 steel there are four regions, H, M, L and G, showing different stress and temperature dependence of creep rupture life. Creep rupture life of Gr. 92 steel increases with increasing hardness after tempering in Regions H and M (high and medium stress), and with increasing prior austenite grain size in long-term Region G. Its creep rupture life is insensitive to the heats in low-stress Region L. Creep rupture lives of the steel are formulated in each region as a function of stress, temperature and a metallurgical variable determining its creep rupture life. Two types of breakdown in creep strength (substantial decrease in stress exponent for creep rupture life) take place in Gr. 92 steel; one from Region M to Region L, and the other from Region M or L to Region G. Since Gr. 92 steel is used in Region G in steam power boilers, the second breakdown to Region G is of engineering importance. Causes of the second breakdown are discussed with creep rupture data of four grades of creep strength enhanced ferritic steels.
AB - The present paper studies stress, temperature and heat dependence of creep rupture life of 9Cr-1.8W-0.5Mo-VNb (Gr. 92) steel with creep rupture data of 4 heats reported in National Institute for Materials Science Creep Data Sheet 48B. In creep of Gr. 92 steel there are four regions, H, M, L and G, showing different stress and temperature dependence of creep rupture life. Creep rupture life of Gr. 92 steel increases with increasing hardness after tempering in Regions H and M (high and medium stress), and with increasing prior austenite grain size in long-term Region G. Its creep rupture life is insensitive to the heats in low-stress Region L. Creep rupture lives of the steel are formulated in each region as a function of stress, temperature and a metallurgical variable determining its creep rupture life. Two types of breakdown in creep strength (substantial decrease in stress exponent for creep rupture life) take place in Gr. 92 steel; one from Region M to Region L, and the other from Region M or L to Region G. Since Gr. 92 steel is used in Region G in steam power boilers, the second breakdown to Region G is of engineering importance. Causes of the second breakdown are discussed with creep rupture data of four grades of creep strength enhanced ferritic steels.
KW - Creep rupture life
KW - Grade 92 steel
KW - Grain size effect
KW - Heat dependence
KW - Multi-region modelling
KW - Strengthening mechanism
UR - http://www.scopus.com/inward/record.url?scp=85099652020&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85099652020&partnerID=8YFLogxK
U2 - 10.1016/j.ijpvp.2021.104312
DO - 10.1016/j.ijpvp.2021.104312
M3 - Article
AN - SCOPUS:85099652020
SN - 0308-0161
VL - 190
JO - International Journal of Pressure Vessels and Piping
JF - International Journal of Pressure Vessels and Piping
M1 - 104312
ER -