발전 설비용 CrMo강의 탄화물 구조와 조성 변화에 미치는 열화 및 크리프 손상의 영향

주연준; 홍경태; 이현웅; 신동혁; 김제원; Y.J. Joo; K.T. Hong; H.W. Lee; D.H. Shin; J.W. Kim

Korean Journal of Materials Research, Vol.9, No.10, 1018-1024, October, 1999

The Effects of Thermal Degradation and Creep Damage on the Microstructure and Composition of the Carbides in the CrMo Steels for Power Plant

주연준, 홍경태, 이현웅¹, 신동혁¹, 김제원²

한국과학기술연구원 금속연구부
¹한양대학교 금속재료공학과
²포항제철 에너지부 에너지기술팀

Y.J. Joo, K.T. Hong, H.W. Lee¹, D.H. Shin¹, and J.W. Kim²

Division of Metals, Korea Institute of Science and Technology, Seoul 136-791, Korea
¹Dept. of Metallurgy & Materials Science, Hanyang University, Ansan Kyunggi-Do, 425-791, Korea
²Energy Technical Team, Pohang Iron & Steel Co., Pohang 790-785, Korea

초록

Sn-3.5Ag 무연합금을 Cu 및 Alloy42 리드프레임에 납땜접합 (solder joint)하고 미세조직, 젖음성, 전단강도, 시효효과를 측정하여 비교하였다. Cu의 경우, 땜납의 Sn기지상안에 Ag(sub)3Sn과 Cu(sub)6Sn(sub)5상이, 그리고 땜납/리드프레임의 경계면에서는 1∼2㎛ 두께의 Cu(sub)6Sn(sub)5상이 형성되었다. Alloy42의 경우, 기지상내에 있는 낮은 밀도의 Ag(sub)3Sn상만이, 그리고 계면에는 0.5∼1.5㎛ 두께의 FeSn(sub)2이 형성되었다. 한편, Cu에 비해 Alloy42 리드프레임에서 퍼짐면적은 크고 접촉각은 작아 더 우수한 젖음성을 나타내었으나, 전단강도는 35%, 연신율은 75%로 낮았다. 180℃에서 1주일간 시효처리 후, Cu 리드프레임에는 계면에 η-Cu(sub)6Sn(sub)5 층외에 ξ-Cu(sub)3Sn층이 성장하였고, Alloy42 리드프레임에는 기지상내에 Ag(sub)3Sn이 구형으로 조대하게 성장하였고, 계면에는 FeSn(sub)2층만이 약 1.5㎛로 성장하였다.

The effects of operating temperature and stress on degradation of components in high temperature steam generator were investigated. Several 2.25CrlMo tubes which had operated over 20 years and an unused 9CrlMoVNb tube were tested. For the former samples, the amount of M 6 C carbide and its size are increased with the aging or operating time. The precipitation behavior of carbides ( M 2 O , M 6 C ) is changed with the operating temperature of the tubes. However, unused 9CrlMoVNb samples show a different carbide precipitation process due to high chromium, vanadium, and niobium contents. The amount of Cr-rich M 23 C 6 carbide is significantly increased with aging time, but that of M 6 C type carbide is rarely changed with aging time at elevated temperatures.

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[1] Williams KR, Whilshire B, Mater. Sci. Eng., 47, 151 (1981)

[2] Abe F, Nakazawa S, Araki H, Noda T, Metall. Trans., 23A, 469 (1992)

[3] Janovec J, Vyrostkova A, Svoboda M, Metall. Trans., 25A, 267 (1994)

[4] Ennis PJ, Zielinska-Lipiec A, Wachter O, Czyrska-Filemonowicz A, Actamater., 45, 4901 (1997)

[5] Vyrostkova A, Kroupa A, Janovec J, Svoboda M, Acta Mater., 46, 31 (1998)

[6] Cheruvu NS, Metall. Trans., 20A, 87 (1989)

[7] Gould GC, Spec. Tech. Publication, 407, 90 (1968)

[8] Williams KR, Whilshire B, Mater. Sci. Eng., 28, 289 (1977)

[9] EPRI CS-5564, Remaining Life Assesment of Superheater and Reheater Tubes/ 1988 (1988)

[10] Abe F, Araki H, Noda T, Metall. Trans., 22A, 2225 (1991)

[11] Klueh RL, Maziasz PJ, Metall. Trans., 20A, 373 (1989)

[12] Watanabe Y, Shoji T, Metall. Trans., 22A, 2097 (1991)

[13] Qu Z, Kuo KH, Metall. Trans., 12A, 1333 (1981)

[14] Afrouze A, Collins MJ, Pilkington R, Metal Technol., 10, 461 (1983)

[15] Jones WB, Hills CR, Polonis DH, Metall. Trans., 22A, 2225 (1991)

[16] Vitek JM, Klueh RL, Metall. Trans., 17A, 1191 (1986)

[17] Tu LKL, Seth BB, Metal Technol., 5, 79 (1978)