Investigator: prof. RNDr. Jaroslav Polák, DrSc., dr. h. c.
Number of Project: IAA2041201
Agency: Grant Agency of the Academy of Sciences of the Czech Republic
Duration: 01. 01. 2001 - 31. 12. 2005

The aim of the proposed project is, in link to previous project on cyclic plasticity, to find the mechanisms of the fatigue damage in advanced materials, preferably in the early stages, when its detection is difficult but when it is decisive for fatigue life. In austenitic, ferritic and austenitic-ferritic duplex steels we shall study the localisation of the cyclic plastic strain, the formation of surface relief, the initiation of natural cracks and the growth of short cracks. Experimental finding on the growth of extrusions and intrusions and on the short crack growth will be confronted with the proposed models in order to improve existing models and obtain information, which can serve in the modification of the structure that result in better fatigue resistance. Important stages of fatigue damage will be identified and parameters that determine the fatigue life will be evaluated. The project will deepen our knowledge on the mechanisms, which results in fatigue fracture.

MAN J, OBRTLÍK K, POLÁK J: Study of surface relief evolution in fatigued 316L austenitic stainless steel by AFM. Mater. Sci. Engng A351 (2003) 123–132.

MAN J, PETRENEC M, OBRTLÍK K, POLÁK J: AFM and TEM study of cyclic slip localization in fatigued ferritic X10CrAl24 stainless steel. Acta Mater. 52 (2004) 5551–5561.

PETRENEC M, OBRTLÍK K, POLÁK J: Inhomogeneous dislocation structure in fatigued INCONEL 713 LC superalloy at room and elevated temperatures. Mater. Sci. Engng A400–401 (2005) 485–488.

PETRENEC M, OBRTLÍK K, POLÁK J, MAN J, HRBÁČEK K: Fatigue behaviour of cast nickel based superalloy INCONEL 792-5A at room temperature. Materials Engineering 12 (2005) 21–24 (in Czech).

PETRENEC M, AUBIN V, POLÁK J, DEGALLAIX S: Dislocation structures of duplex stainless steel in uniaxial and biaxial cyclic loading. Mater. Sci. Forum 482 (2005) 179–182.

POLÁK J, PETRENEC M, DEGALLAIX S: On the analysis of the hysteresis loop of ferritic steel in cyclic straining. Scripta Mater. 47 (2002) 731–736.

POLÁK J, MAN J, OBRTLÍK K: AFM evidence of surface relief formation and models of fatigue crack nucleation. Int. J. Fatigue 25 (2003) 1027–1036.

POLÁK J, MAN J, OBRTLÍK K, KRUML T: The shape of extrusions and intrusions produced by cyclic straining. Z. Metallkde. 94 (2003) 1327–1330.

POLÁK J, MAN J, OBRTLÍK K: Atomic force microscopy study of the early fatigue damage. Mater. Sci. Forum 482 (2005) 45-50.

POLÁK J, PETRENEC M, MAN J: Dislocation structure and surface relief in fatigued metals. Mater Sci. Engng A400-401 (2005) 405-408.

POLÁK J: Plastic strain controlled short crack growth and fatigue life. Int. J. Fatigue 27 (2005) 1192-2001.