PSI - Issue 23

Ladislav Poczklán et al. / Procedia Structural Integrity 23 (2019) 269–274 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 6 a) Length of the crack as a function of the number of cycles for three different types of cycling with the same equivalent total strain amplitude 0.44 % b) Crack growth rate as a function of the crack length.

4. Conclusions

The most important findings of this study can be summarized in following points:

 PSBs are formed during the cycling in all three modes and fatigue cracks initiate from them.  Dislocations were rearranged during the cycling, deformation twins were formed and finally, phase transformation from austenite to α´ martensite occurred.  The smallest crack growth rate was observed in pure torsional loading mode. This could be caused by more intense phase transformation and by differences in details of crack growth. Acknowledgements The financial support of project 18-03615S, Grant Agency of the Czech Republic, is gratefully acknowledged. This research has been supported by the Ministry of Education, Youth and Sports of the Czech Republic under the projects m-IPMinfra (CZ.02.1.01/0.0/0.0/16_013/0001823). Alain, R., Violan, P., and Mendez, J. (1997) Low cycle fatigue behavior in vacuum of a 316L type austenitic stainless steel between 20 and 600 degrees C. Part 1: Fatigue resistance and cyclic behaviour. Materials Science and Engineering A, 229, pp. 87-94. Gerland, M., Mendez, J., Violan, P., Saadi, B. (1989) Evolution of Dislocation-Structures and Cyclic Behavior of a 316l-Type Austenitic Stainless-Steel Cycled Invacuo at Room-Temperature. Materials Science and Engineering A , 118, pp. 83-95. Jacquelin, B., Hourlier, F., and Pineau, A. (1983) Crack Initiation under Low-Cycle Multiaxial Fatigue in Type-316l Stainless-Steel. Journal of Pressure Vessel Technology, 105, pp. 138-143. Kruml, T., Polák, J., Degallaix , S. (2000) Microstructure in 316LN stainless steel fatigued at low temperature. Materials Science and Engineering A , 293, pp. 275-280. Li, Y. and Laird, C. (1994) Cyclic Response and Dislocation Structures of AISI 316L Stainless-Steel. Part 2: Polycrystals Fatigued at Intermediate Strain Amplitude. Materials Science and Engineering A , 186, pp. 87-103. Lu, J., Hultman, L., Holmström, E., Antonsson, K.H., Grehk, M., Li, W., Vitos, L., Golpayegani, A. (2016) Stacking fault ener gies in austenitic stainless steels, Acta Materialia , 111, pp. 39-46. Mazánová, V., Škorík, V., Polák, J., Kruml, T. (2017) Cyclic response and early damage evolution in multiaxial cyclic loading of 316L austenitic steel. Int. J. Fatigue , 100, pp. 466-476. Polák, J. and Man, J. (2014) Mechanisms of extrusion and intrusion formation in fatigued crystalline materials. Materials Science and Engineering A , 596, pp. 15-24. Polák, J. and Zezulka, P. (2005), Short crack growth and fatigue life in austenitic-ferritic duplex stainless steel, Fatigue Fract Engng Mater Struct., 28, pp. 923 – 935. Tanaka, K., Mura, T. (1982) A Theory of Fatigue Crack Initiation at Inclusions. Metallurgical Transactions A , 13, pp. 117-123. Vogt, J.B., Foct, J., Regnard, C., Robert, G., Dhers, J. (1991) Low-Temperature Fatigue of 316L and 316LN Austenitic Stainless Steels. Metallurgical Transactions A , 22, pp. 2385-2392 . References