Investigator: Ing. Jiří Man, Ph.D.
Number of Project: 106/00/D055
Agency: Czech Science Foundation
Duration: 01. 09. 2000 - 31. 08. 2003

The project was focused on understanding of cycle asymmetry effect on early fatigue damage stages in structural materials (316L austenitic stainless steel, nickel base superalloy). Attention was paid to the study of mean stress effect on surface relief accompanying fatigue crack initiation. Surface relief was studied using high-resolution microscopy techniques – SEM and AFM. The experimental characteristics concerning to the slip activity in individual grains, to the surface relief evolution in dependence on applied loading conditions (plastic strain amplitude, mean stress value) and on the number of cycles were determined. Experimental results obtained were analysed and quantified in terms of the static and cyclic contributions.

MAN J, OBRTLÍK K, BLOCHWITZ C, POLÁK J: Atomic Force Microscopy of surface relief in individual grains of fatigued 316L austenitic stainless steel. Acta Mater. 50 (2002) 3767–3780.

MAN J, VIČAR M, POLÁK J, OBRTLÍK K: Slip localization and surface relief evolution in fatigued ferritic X10CrAl24 stainless steel. Materials Engineering 9 (2002) 140–145 (in Czech).

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.

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.