Effect of thermal aging on the fatigue crack growth behavior of cast duplex stainless steels

Abstract

The effect of thermal aging on the fatigue crack growth (FCG) behavior of Z3CN20?09M cast duplex stainless steel with low ferrite content was investigated in this study. The crack surfaces and crack growth paths were analyzed to clarify the FCG mechanisms. The microstructure and micromechanical properties before and after thermal aging were also studied. Spinodal decomposition in the aged ferrite phase led to an increase in the hardness and a decrease in the plastic deformation capacity, whereas the hardness and plastic deformation capacity of the austenite phase were almost unchanged after thermal aging. The aged material exhibited a better FCG resistance than the unaged material in the near-threshold regime because of the increased roughness-induced crack closure associated with the tortuous crack path and rougher fracture surface; however, the tendency was reversed in the Paris regime because of the cleavage fracture in the aged ferrite phases.

Keywords

stainless steels / fatigue crack growth / thermal aging / embrittlement / fracture morphology

References

[1] Chung H.M. Aging and life prediction of cast duplex stainless steel components. Int. J. Pressure Vessels Piping, 1992, 50(1–3): 179.

[2] Weng K.L., Chen H.R., Yang J.R. The low-temperature aging embrittlement in a 2205 duplex stainless steel. Mater. Sci. Eng. A, 2004, 379(1–2): 119.

[3] Pareige C., Novy S., Saillet S., Pareige P. Study of phase transformation and mechanical properties evolution of duplex stainless steels after long term thermal ageing (> 20 years). J. Nucl. Mater., 2011, 411(1–3): 90.

[4] Bonnet S., Bourgoin J., Champredonde J., Guttmann D., Guttmann M. Relationship between evolution of mechanical properties of various cast duplex stainless steels and metallurgical and aging parameters: outline of current EDF programmes. Mater. Sci. Technol., 1990, 6(3): 221.

[5] Chung H.M., Leax T.R. Embrittlement of laboratory and reactor aged CF3, CF8, and CF8M duplex stainless steels. Mater. Sci. Technol., 1990, 6(3): 249.

[6] Danoix F., Auger P. Atom probe studies of the Fe–Cr system and stainless steels aged at intermediate temperature: a review. Mater. Charact., 2000, 44(1–2): 177.

[7] Marrow T.J., King J.E. Fatigue crack propagation mechanisms in a thermally aged duplex stainless steel. Mater. Sci. Eng. A, 1994, 183(1–2): 91.

[8] Nyström M., Karlsson B. Fatigue of duplex stainless steel influence of discontinuous, spinodally decomposed ferrite. Mater. Sci. Eng., A, 1996, 215(1–2): 26.

[9] Iturgoyen L., Anglada M. The influence of ageing at intermediate temperatures on the mechanical behaviour of a duplex stainless steel: Part II. Fatigue life and fatigue crack growth. Fatigue Fract. Eng. Mater. Struct., 1997, 20(6): 917.

[10] Iacoviello F., Boniardi M., Vecchia G.M.L. Fatigue crack propagation in austeno-ferritic duplex stainless steel 22Cr5Ni. Int. J. Fatigue, 1999, 21(9): 957.

[11] Calonne V., Gourgues A.F., Pineau A. Fatigue crack propagation in cast duplex stainless steels: thermal ageing and microstructural effects. Fatigue Fract. Eng. Mater. Struct., 2004, 27(1): 31.

[12] Xue F., Wang Z.X., Shu G.G., Yu W.W., Shi H.J., Ti W.X. Thermal aging effect on Z3CN20.09M cast duplex stainless steel. Nucl. Eng. Des., 2009, 239(11): 2217.

[13] Yao Y.H., Wei J.F., Wang Z.P. Effect of long-term thermal aging on the mechanical properties of casting duplex stainless steels. Mater. Sci. Eng. A, 2012, 551, 116.

[14] Li S.L., Wang Y.L., Li S.X., Zhang H.L., Xue F., Wang X.T. Microstructures and mechanical properties of cast austenite stainless steels after long-term thermal aging at low temperature. Mater. Des., 2013, 50, 886.

[15] Li S.L., Wang Y.L., Zhang H.L., Li S.X., Zheng K., Xue F., Wang X.T. Microstructure evolution and impact fracture behaviors of Z3CN20-09M stainless steels after long-term thermal aging. J. Nucl. Mater., 2013, 433(1–3): 41.

[16] American Society for TestingMaterials. ASTM E647-11 Standard Test Method for Measurement of Fatigue Crack Growth Rates, 2011

[17] Sahu J.K., Krupp U., Ghosh R.N., Christ H.J. Effect of 475°C embrittlement on the mechanical properties of duplex stainless steel. Mater. Sci. Eng. A, 2009, 508(1–2): 1.

[18] Li S.L., Zhang H.L., Wang Y.L., Li S.X., Zheng K., Xue F., Wang X.T. Annealing induced recovery of long-term thermal aging embrittlement in a duplex stainless steel. Mater. Sci. Eng. A, 2013, 564, 85.

[19] Chandra K., Singhal R., Kain V., Raja V.S. Low temperature embrittlement of duplex stainless steel: Correlation between mechanical and electrochemical behavior. Mater. Sci. Eng. A, 2010, 527(16–17): 3904.

[20] Liu P., Lu F.G., Liu X., Ji H.J., Gao Y.L. Study on fatigue property and microstructure characteristics of welded nuclear power rotor with heavy section. J. Alloys Compd., 2014, 584, 430.

[21] Stolarz J., Foct J. Specific features of two phase alloys response to cyclic deformation. Mater. Sci. Eng. A, 2001, 319–321, 501.

[22] Korda A.A., Mutoh Y., Miyashita Y., Sadasue T., Mannan S. In situ observation of fatigue crack retardation in banded ferrite–pearlite microstructure due to crack branching. Scripta Mater., 2006, 54(11): 1835.

[23] Korda A.A., Mutoh Y., Miyashita Y., Sadasue T. Effects of pearlite morphology and specimen thickness on fatigue crack growth resistance in ferritic–pearlitic steels. Mater. Sci. Eng. A, 2006, 428, 262.

[24] Suresh S. Fatigue of Materials, 1998, Cambridge, Cambridge University Press

[25] Mutoh Y., Korda A.A., Miyashita Y., Sadasue T. Stress shielding and fatigue crack growth resistance in ferritic–pearlitic steel. Mater. Sci. Eng. A, 2007, 468, 114.

[26] Kato M. Hardening by spinodally modulated structure in bcc alloys. Acta Metall., 1981, 29(1): 79.

[27] Park K.H., LaSalle J.C., Schwartz L.H., Kato M. Mechanical properties of spinodally decomposed Fe-30 wt% Cr alloys: Yield strength and aging embrittlement. Acta Metall., 1986, 34(9): 1853.

[28] Noroozi A.H., Glinka G., Lambert S. A study of the stress ratio effects on fatigue crack growth using the unified two-parameter fatigue crack growth driving force. Int. J. Fatigue, 2007, 29(9–11): 1616.