Cyclic Deformation Induced Residual Stress Evolution and 3D Short Fatigue Crack Growth Investigated by Advanced Synchrotron Tomography Techniques

Dönges, Benjamin; Syha, M.; Hüsecken, A.K.; Pietsch, U.; Ludwig, Wolfgang; Krupp, Ulrich; Christ, Hans‐Jürgen

doi:10.3390/ma14061562

Cited by 2 publications

(1 citation statement)

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“…Furthermore, for a more detailed and quantitative analysis, high-resolution 3D examination techniques such as diffraction contrast synchrotron tomography should be applied. [37]…”

Section: Discussionmentioning

confidence: 99%

Characterizing the Fatigue Damage in a Martensitic Spring Steel

Wildeis

Christ

Brandt

et al. 2021

steel research int.

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Many technical components are subjected to uniaxial cyclic loading in the high cycle fatigue regime. The resulting fatigue damage evolution is commonly subdivided into four stages, i.e., crack initiation, short crack propagation, long crack propagation, and eventually failure. Especially, the stages of crack initiation and short crack propagation can account for up to 90% of the fatigue life in the high cycle fatigue regime, leading to a particular interest in investigating these stages of fatigue damage evolution. [1] Furthermore, it is extremely important to understand the mechanisms of crack initiation and short crack propagation for lifetime predictions of structures which are not fail safe, as their failure can cause a catastrophic damage.Many studies have shown, that crack initiation often occurs at slip bands (see for example, the studies by Christ, McEvily, Efthymiadis et al., and Hong et al. [1][2][3][4] ) and that short crack propagation is strongly influenced by the local microstructure, leading to an oscillating crack propagation rate (see for example, the studies by Christ, McEvily, Miller, and Yang et al. [1,2,5,6] ). However, until now, just a few studies have investigated the fatigue damage evolution in a martensitic steel and the corresponding impact of the complex martensitic microstructure on the crack initiation and the short crack propagation. The crack initiation in martensitic steels seems to occur often at slip bands, [7][8][9][10][11] which mainly arise at microstructural interfaces and are oriented parallel to martensitic laths. [11][12][13] It seems that those slip bands do not cross microstructural interfaces with a high-angle boundary like packet boundaries or prior austenite grain boundaries (PAGBs). [10,13,14] Hence, the crack initiation and early short crack propagation in martensitic steels seem to occur mainly intergranularly at PAGBs [11,12,14,15] or block boundaries, [11,16] although in some studies, transgranular crack initiation and early short crack propagation were also observed. [9,13] In many studies, the preferential alignment of carbides along microstructural interfaces is cited as a possible reason for intergranular crack initiation and early short crack propagation. [7,14,17,18] In addition, intergranular crack initiation can be explained by the impingement of slip bands on grain boundaries [14,19,20] or the anisotropic elastic and plastic properties of the grains. [11,12,15,[21][22][23] The number of slip bands formed and cracks initiated rises with increasing number of cycles and with increasing stress amplitude. [4,8,9,13,24] The subsequent short crack propagation seems to be strongly influenced by the local microstructure, whereby a short crack propagation parallel to the martensitic laths is often observed. [8,24,25] PAGBs [6,8,14,24,26] and block boundaries [6,7,26] seem to act as obstacles for short crack propagation, leading to an oscillating short crack propagation rate. An often referred explanation for the barrier effect of microstructural interfaces is the...

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“…Furthermore, for a more detailed and quantitative analysis, high-resolution 3D examination techniques such as diffraction contrast synchrotron tomography should be applied. [37]…”

Section: Discussionmentioning

confidence: 99%