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 - Funding Information:
The authors could accomplish the present analyses with the aid of the high-quality data published in NIMS Creep Data Sheet No. 48B. The authors thank National Institute for Materials Science for the publication of the creep data sheets. The present study was financially supported by Japan Science and Technology Agency , Japan through an ALCA program grant No. JPMJAL1101. The time-temperature-parameter analyses of creep rupture data were performed with the excel program file developed by R.W. Swindeman and his co-workers. The program file was produced for use in Boiler and Pressure Vessel Code Committee, the American Society of Mechanical Engineers. The authors deeply acknowledge Dr. R.W. Swindeman and his co-workers for providing the program file.
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
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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 -