Fatigue Behaviour of Stainless Steel Used for Turbine Runners

Abstract:

The key ingredient for any turbine runners design procedure and failure analysis is the material and its mechanical and fatigue properties. Starting from this observation, a series of static and dynamic tests were performed on the T10CuNiCr180 stainless steel after more than three decades of service. The fatigue tests were carried out under constant amplitude at a stress ratio of 0.1 and a frequency of 20 Hz. In the high cycle fatigue range, the S-N median curve was plotted and the fatigue limit for 310⁶ cycles to failure was determined at 93.35 [MPa] expressed in stress amplitude. The casting and welding defects that were observed on fracture surfaces explained this lower fatigue limit. The fatigue crack growth tests were performed on compact tension specimens and a three-parameter model was used to plot the crack length versus number of cycles curves. In addition, the material constants from Paris law were determined. Finally, the experimental results are compared against published data for another stainless steel.

• Periodical: Advanced Engineering Forum (Volumes 8-9)
• Pages: 413-420
• DOI: https://doi.org/10.4028/www.scientific.net/AEF.8-9.413
• Online since: June 2013
• Authors: Radu Negru, Liviu Marsavina, Sebastian Muntean, Niculai Pasca
• Keywords: Fatigue Crack Growth (FCG), S-N Curve, Stainless Steel (SS)

References

[1] A. Baya, S. Muntean, V.C. Campian, A. Cuzmos, M. Diaconescu, M. Balan, Experimental investigations of the unsteady flow in a Francis turbine draft tube cone, IOP Conf. Ser.: Earth Environ. Sci. 12 (2010) 012007.

DOI: 10.1088/1755-1315/12/1/012007

[2] D. Frunzaverde, S. Muntean, G. Marginean, V. Campian, L. Marsavina, R. Terzi, V. Serban, Failure analysis of a Francis turbine runner, IOP Conf. Ser.: Earth Environ. Sci. 12 (2010) 012115.

DOI: 10.1088/1755-1315/12/1/012115

[3] D. Chiorean, I. Rogoz, I. Poienariu, Technical problems arising from the operation of hydraulic turbines at SHC, Timisoara Academic Days, XI Edition, Timisoara, (2009) 1-8.

[4] N. Pasca, L. Marsavina, S. Muntean, R. Negru: submitted to Engineering Failure Analysis (2013).

[5] H. Brekke, Performance and safety of hydraulic turbines, IOP Conf. Ser.: Earth Environ. Sci. 12 (2010) 012061.

DOI: 10.1088/1755-1315/12/1/012061

[6] S. Muntean, I. Ninaci, R. Susan-Resiga, A. Baya, I. Anton, Numerical analysis of the flow in the old Francis runner in order to define the refurbishment strategy, UPB Scientific Bulletin Series D: Mechanical Engineering 72 (2010) 117-124.

[7] J. Roesler, H. Harders, M. Baeker, Mechanical Behaviour of Engineering Materials, Springer-Verlag, Berlin, (2007).

[8] ASM Handbook, vol. 8, Mechanical Testing and Evaluation, ASM International, Materials Park, (2000).

[9] N. Natsume, Y. Hayashi, H. Akebono, M. Kato, A. Sugeta, Fatigue properties and crack propagation behavior of stainless cast steel for turbine runner of hydraulic power generation, J. Proc. Eng. 2 (2010) 1273-1281.

DOI: 10.1016/j.proeng.2010.03.138

[10] H. Nakazawa, S. Kodama, Statistical fatigue testing method with 14 specimens – JSME standard method for determination of S-N curves, in: T. Tanaka, S. Nishijima, M. Ichikawa (Eds. ), Statistical Research on Fatigue and Fracture (Current Japanese Materials Research, vol. 2), Elsevier Applied Science Publishers Ltd., Essex, England, 1987, pp.59-69.

[11] Y.L. Lee, J. Pan, R.B. Hathaway, M.E. Barkey, Fatigue Testing and Analysis (Theory and Practice), Elsevier Butterworth-Heinemann, Burlington, (2005).

[12] C.L. Shen, P.H. Wirshing, G.T. Cashman, Design curve to characterize fatigue strength, J. Eng. Mater. -T. ASME 118 (1996) 535-541.

DOI: 10.1016/s0142-1123(97)82623-0

[13] C.R. Williams, Y. Lee, J.T. Rilly, A practical method for statistical analysis of strain-life fatigue data, Int. J. Fatigue 25 (2003) 427-436.

DOI: 10.1016/s0142-1123(02)00119-6

[14] W.J. Dixon, A.M. Mood, A method for obtaining and analyzing sensitivity data, J. Am. Stat. Assoc. 43 (1948) 109-126.

[15] A. De Iorio, M. Grasso, F. Penta, G.P. Pucillo, A three-parameter model fatigue crack growth data analysis, Frattura ed Integrita Strutturale 21 (2012) 21-29.

DOI: 10.3221/igf-esis.21.03

[16] P.C. Paris, F. Erdogan, A critical analysis of crack propagation laws, J. Basic Eng. -T. ASME 85 (1963) 528-534.

DOI: 10.1115/1.3656902

[17] K. Walker, The effects of stress ratio during crack propagation and fatigue for 2024-T3 and 7075-T6 aluminum, in: Effects of Environment and Complex Load History for Fatigue Life, ASTM STP 462, Philadelphia, 1970, pp.1-14.

DOI: 10.1520/stp32032s

[18] O. Wheeler, Spectrum loading and crack growth, J. Eng. Mater. -T. ASME 94 (1972) 181-186.