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Vol.44, No.11, 741 ~ 752, 2006
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| Title |
| Embrittlement Behaviors of Isothermally Heat-Treated T/P91 Steel at 350℃ |
| 김성용 Sung Yong Kim , 이재현 Jae Hyun Lee , 배창환 Chang Wan Bae , 김정태 Jung Tae Kim , 구자민 Ja Min Koo , 허성강 Sung Kang Hur |
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| Abstract |
| In these days, T/P91 steel is widely used for boiler tubes of ultra super critical (USC) power plants. However, the usage is greatly restricted by the embrittlement observed in the steel. In this study, microstructural analyses with various mechanical tests were performed to determine the embrittlement mechanism in T/P91 (Modified 9Cr-lMo-V-Nb). As a result, a mechanism of embrittlement based on the stabilization of martensite was found in the steel, when it was quenched to and retained for two hours at a temperature between Ms and Mf, and then air-cooled. The severity of the embrittlement is believed to depend on the carbon content and the volume fraction of the fresh martensite which has been formed during the air-cooling. The above mechanism well explained the experimental results including the pre and post heat-treatment effect on the embrittlement. |
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| Key Words |
| embrittlement, T/P91 steel, isothermal heat-treatment, martensite |
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