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Towards understanding fracture initiation in nanotribology

Thursday (27.09.2018)
11:45 - 12:00 S1/01 - A5
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Fracture in metals occurs by microcrack initiation, microcrack growth and coalescence. Tribological crack formation mechanism traditionally is related to surface fatigue. However, Crack can form even in single stroke scratch track. Furthermore, grain crystal orientation can determine crack formation [1, 2]. Here, since the mechanism of crack formation during single stroke scratch is still not clear, we try to identify the relationship between micro-cracking, micro-plowing and grain orientation during single stroke scratch, and then reveal the basic mechanisms of crack initiation and growth in one grain and grain orientation dependent crack formation. In this study, we carry out the single stroke scratch experiments on 304 steel (FCC metal) and FeCr20 alloy (BCC metal). The Scanning Electron Microscopy (SEM) and Electron Back-Scatter Diffraction (EBSD) are used to characterise the crack morphology and grain orientation after scratch tests. The Focused-Ion-Beam milling (FIB) is applied to make cross-sections of scratch tracks to quantify the crack length, crack opening width, and determine the crack growth direction. The fundamental understanding of crack initiation and growth in microscale will improve the macroscale understanding of wear and friction in engineering area.

[1] S. Brinckmann, C. Fink, and G. Dehm. “Nanotribology in austenite: normal force dependence”. Wear. 338-339 (2015), pp. 430–435.

[2] S. Brinckmann and G. Dehm. “Nanotribology in austenite: evolution of plasticity”. Wear. 338-339 (2015), pp. 436–440.

Dr. Wenzhen Xia
Max-Planck-Institut für Eisenforschung GmbH
Additional Authors:
  • Dr. Steffen Brinckmann
    Max-Planck-Institut für Eisenforschung GmbH
  • Prof. Dr. Gerhard Dehm
    Max-Planck-Institut für Eisenforschung GmbH