Browse > Article

Behavior of the Residual Stress on the Surfaces of 12Cr Steels Generated by Flame Hardening Process  

이민구 (한국원자력연구소 원자력재료기술개발부)
김광호 (한국원자력연구소 원자력재료기술개발부)
김경호 (한국원자력연구소 원자력재료기술개발부)
김흥회 (한국원자력연구소 원자력재료기술개발부)
Publication Information
Journal of the Korean institute of surface engineering / v.37, no.4, 2004 , pp. 226-233 More about this Journal
Abstract
The residual stresses on the surfaces of low carbon 12Cr steels used as a nuclear steam turbine blade material have been studied by controlling the flame hardening surface treatments. The temperature cycles on the surfaces of 12Cr steel were controlled precisely as a function of both the surface temperature and cooling rate. The final residual stress state generated by flame hardening was dominated by two opposite competitive contributions; one is tensile stress due to phase transformation and the other is compressive stress due to thermal contraction on cooling. The optimum processing temperatures required for the desirable residual stress and hardness were in the range of $850^{\circ}C$ to $960^{\circ}C$ on the basis of the specification of GE power engineering. It was also observed that the high residual tensile stress generated by flame hardening induced the cracks on the surfaces, especially across the prior austenite grain boundaries, and the material failure virtually, which might limit practical use of the surface engineered parts by flame hardening.
Keywords
Surface treatment; Flame hardening; 12Cr steel; Hardness; Residual stress; Martensitic transformation;
Citations & Related Records
연도 인용수 순위
  • Reference
1 E. Hoegger, Brown Boveri Rev., 14 (1927) 95
2 M. Cohen, Trans. AIME, 224 (1962) 638
3 R. J. Ackert, R. W. Witty, P. A. Crozier, US Patent 4486248 (1982)
4 S. Toyoaki, Japanese Patent 64-39327 (1989)
5 R. Araki, M. Kisimoto, K. Yoshida, JSME International Journal, 34 (1991) 397
6 J. Grum, S. Bozic, M. Zupancic, J. Mater. Proc. Technol, 114 (2001) 57   DOI   ScienceOn
7 I. Kyoji, Japanese Patent 61-113712 (1986)
8 F. J. Heymann, J. Appl. Phys., 40 (1969) 5113   DOI
9 O. G. Engel, J. Res. Nat. Bur. Stand., 54 (1955) 283
10 J. M. Marder, A. R. Marder, Trans. ASM, 62 (1969) 1
11 Process Specification, Materials and Process Engineehng, GE Power Engineehng, Schenectady, NY (1995), 14
12 M. Heitkemper, C. Bohne, A. Pyzalla, A. Fischer, Int. J. Fatigue, 25 (2003) 101
13 B. D. Cullity, Elements of X-ray Diffraction (Addison-Wesley, Reading, MA) 2nd ed., (1978) 447
14 K. Schleithoff, F. Schmitz, Corrosion Fatigue of Steam Turbine Blade Materials, Workshop Proceedings, edited by R.I. Jaffee, Palo Alto, CA, Sep. 21-24, EPRI, Pergamon Press, (1981) 70
15 R. H. Aborn, Trans. ASM, 48 (1950) 51
16 M. K. Lee, G. H. Kim, K. H. Kim, W. W. Kim, Surf. Coat. Tech., 184 (2004) 239   DOI   ScienceOn
17 Y. Ishiki, K. Nakamura, S. Takegami, Titanium Steam Turbine Blading, Workshop Proceedings, edited by R.I. Jaffee, Palo Alto, CA, Nov. 9-10, EPRI, Pergamon Press, (1988) 62