Project Area C: Characterization – Material Load and Modification

The subprojects (SP) in this project area are using complementary methods for a comprehensive description of the physical and chemical properties to analyze the material load and modification. With high-resolution measurement techniques, it should be possible to fundamentally interpret observed phenomena and to transfer them into models in cooperation with projects of area M. For this purpose it is necessary to perform the analyses also on different scales. It is to be expected that new analyzing methods will be developed, which expand the state-of-the-art in the area of material and process description.


SP C01 – Analysis of materials modification by diffraction methods

The surface near properties changed in process chains or process sequences are analyzed using X-ray diffraction methods and the material modifications are determined quantitatively depending on the initial state. These results are used to develop process signatures for residual stresses, dislocation density or crystallite size. During in-situ investigations, additional loads are applied to the machined surfaces under controlled conditions, thus determining the specific material behaviour. In addition, methods are being developed to carry out in-situ experiments during grinding or deep rolling at the synchrotron in order to allow the analysis of the internal material loads in the process below the contact point and to relate this to the resulting material modifications.

The current results in SP C01 are summarized here on one page.

PIs: Prof. Dr.-Ing. Hans Werner Zoch, Dr.-Ing. Jeremy Epp

SP C02 – Analysis of the modification of state variables via high resolution microstructure analysis

In the project a combination of high resolution SEM, FIB and TEM investigations will be applied to establish a fundamental understanding of the impact of materials modifications in production processes and of the alterations caused in the near surface zone. The aim is to quantitatively establish the characteristic materials and surface properties before and after machining and to relate them to characteristic changes in the state variables. Furthermore, an understanding of the underlying mechanisms will be sought in in situ experiments in a large chamber SEM.

The current results in SP C02 are summarized here on one page.

PI: Prof. Dr. rer. nat. Joachim Mayer


SP C03 – Surface and Near Surface Characterization of Mechanical and Chemical Properties

The goal of this sub-project is to explore the resulting changes in both the mechanical and chemical state of the surface and near surface of workpieces caused by various machining processes. The measured changes will aid towards developing an understanding of the dissipative and transport processes at work. This information will provide a component to process signatures, which will be developed. For the mechanical characterizations nanoindentation will be used. Raman spectroscopy will be applied to investigate shifts in the chemical state caused by processing and Rutherford backscattering spectrometry (RBS) will be used to investigate the resulting lattice disorder and depth of subsurface damage.

The current results in SP C03 are summarized here on one page.

PI: Prof. Dr. Dr. h. c. Don A. Lucca


SP C04 – In situ measurement of mechanical and thermal material loads

The goal of the project C04 is to develop and test calibrated measurement procedures, which are used to locally measure the elongation and temperature of the workpiece material in process with high resolution. The measurement procedures are based on embedded thin film sensors and optical measurement principles. They surpass the state of the art significantly. The measured properties describe important material loads, which in combination with changes of state variables of the workpiece surface layer enable the development of process signatures.

The current results in SP C04 are summarized here on one page.

PIs: Prof. Dr.-Ing. Walter Lang


SP C06 – Areal optical measurement of mechanical material loads

A time-resolved, area-based in-process measurement of component deformations is essential for the development of process signatures and the determination of material loads. Subproject C06 therefore investigates deformation-based stresses and modifications of workpieces in different manufacturing processes. The digital speckle photography (DSP) method successfully introduced in the first phase of SFB is used for the measurements. Especially adapted evaluation algorithms and measuring systems enable the DSP to be used in-process even on fast-rotating systems with deformation resolutions of less than 20 nm.

The current results in SP C06 are summarized here on one page.

PI: Prof. Dr.-Ing. Andreas Fischer