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@PHDTHESIS{Broemmelhoff:317353,
      author       = {Broemmelhoff, Katrin},
      othercontributors = {Reimers, Prof. Dr. W.},
      title        = {{U}ntersuchungen zur {S}panbildung metallischer
                      {W}erkstoffe anhand von in situ
                      {R}öntgenbeugungsexperimenten},
      school       = {Technische Universität Berlin},
      type         = {Dr.},
      publisher    = {Universität Berlin},
      reportid     = {PUBDB-2017-00632},
      pages        = {1-154},
      year         = {2016},
      note         = {Technische Universität Berlin, Diss., 2016},
      abstract     = {For the optimization of machining processes with
                      geometrically defined cutting edge afundamental
                      understanding of the chip formation process is necessary.
                      However it islimited due to the hard metrological
                      detectability of the area of action. Modern sourcesfor high
                      energetic synchrotron radiation and new detectors enable in
                      situ diffractionexperiments during the cutting process
                      within a very small gauge volume.In the present study the
                      method of in situ diffraction with high-energy
                      synchrotronX-radiation was used for the first time for a
                      comprehensive study of the chip formationprocess during
                      orthogonal cutting experiments. Information about the
                      microstructuraldevelopment in terms of local microstrains,
                      domain sizes, stacking fault probabilitiesand preferred
                      crystal orientations as well as the spatially resolved
                      stress states withinthe chip formation zone have been
                      obtained from diffraction data. For the workpiecesteel C45E
                      with bcc structure and the fcc aluminium alloy AlCuMg1 the
                      influenceof the cutting parameters were studied through a
                      variation of the undeformed chipthickness, the cutting edge
                      radius and the rake angle. On the basis of the results
                      frombrass alloys CuZn10, CuZn37 and CuZn40 the influence of
                      the stacking fault energyand the influence of a second phase
                      have been investigated for various rake angles.A significant
                      dependence of the maximum stresses on the rake angles was
                      observed.The maximum stresses increase upon a decreasing
                      rake angle. In contrast, the maximumstresses do not show a
                      significant dependence on the undeformed chip thicknessand
                      the cutting edge radius. However, a significant dependence
                      of the stress gradientswas observed. Stronger stress
                      gradients can be observed with smaller undeformedchip
                      thickness, smaller cutting edge radius and higher rake
                      angles. During chip formationa strong decrease in domain
                      sizes and an increase in microstrains can be observedwhich
                      proves a strong strain hardening within the chip.The
                      microstructural gradients show identical behaviour as the
                      macroscopic stresses,exhibiting a clear relation between the
                      microstructural development and the evolvingstress state.A
                      further strain hardening was proven within the observed
                      built-up edges, due to thedecrease in domain sizes and an
                      increase in microstrains. The strain hardening resultsin an
                      increase in the von Mises stresses and the hydrostatic
                      stresses.For the first time, the results of a cutting
                      simulation could be compared to experimentaldata. It was
                      concluded that the appearing differences between experiment
                      andsimulation are mainly addressed to the disregard of the
                      strong microstructural developmentand the resulting strain
                      hardening of the material. Using the shear angle relationof
                      OPITZ and HUCKS it could be shown that the experimental data
                      on the stress statesin the chip formation zone can be used
                      to verify and extend existing chip formationmodels. It is
                      shown that the assumption of a free chip flow could not be
                      hold. Therefore,a extension of the relation considering the
                      normal stresses in direction of the chipflow is necessary
                      for a correct calculation of the shear angle.},
      cin          = {DOOR},
      cid          = {I:(DE-H253)HAS-User-20120731},
      pnm          = {6G3 - PETRA III (POF3-622)},
      pid          = {G:(DE-HGF)POF3-6G3},
      experiment   = {EXP:(DE-H253)P-P07-20150101},
      typ          = {PUB:(DE-HGF)11},
      doi          = {10.3204/PUBDB-2017-00632},
      url          = {https://bib-pubdb1.desy.de/record/317353},
}