• Separation of surface and volume damage due to HCF/VHCF loading to identify the re-use potential of quenched and tempered steels

In order to be able to use the pre-damaged components again in new machines and systems after reconditioning, a quantitative evaluation is required, which makes it possible to distinguish between surface and volume damage.Within the scope of the project, the quenched and tempered steel 42CrMo4 is pre-damaged in the HCF range, the damaged volume is removed and, after reconditioning, subjected to a secondary loading in the VHCF range in order to determine the reuse potential. During the tests, the material reaction is characterized in-situ by means of resistometry, thermometry and magnetic field measurement, and subsequently by scanning electron microscopy, which can be used to predict service life.

DFG STA 1133/20-1, Cooperation project with the IEHK, RWTH Aachen University

• Characterization of materials and structures by scanning electron microscopy and EDX, EBSD and STEM analytics

Currently, a scanning electron microscope with additional EDX, EBSD and STEM analytics, funded by the DFG, is being procured. In the future, the diverse application possibilities of this device for the characterisation of materials should offer a great contribution to the interdisciplinary linking of research fields of the various disciplines at Kaiserslautern University of Applied Sciences and significantly increase the potential of the research-active professors.

DFG INST 252/27-1

• Quantified evaluation of the influence of stress frequency on the fatigue behavior of unalloyed steels for implementation in resource-efficient service life prediction methods

Within the work programme of the research project, the established fatigue life prediction (LPV) procedures for the HCF range at test frequencies of 5 Hz are extended for high test frequencies (up to 260 Hz) and high numbers of cycles. The aim is to describe the transition between LCF/HCF up to the VHCF range. Currently, fatigue tests with the steel SAE 1045 in normalised condition are carried out to extend the life prediction methods and confirmed by a detailed characterisation of the microstructure by means of different scanning electronic investigations.

DFG STA 1133/22-1, Cooperation project with the WPT, TU Dortmund University

• Utilisation of statistical approaches within the scope of fatigue life prediction methods for notched specimens using the example of unalloyed steels

The aim of the proposed research project is to develop a fatigue life prediction method (LPV) that enables the most accurate prognosis possible with regard to cyclic deformation behaviour and (residual) fatigue life despite a reduced specimen effort. An essential aspect is the application of parametric and non-parametric mathematical models, which enable a statistical validation of the results obtained. As a first step towards the provision of component fatigue curves using LPV, a further aim is to also improve the measurement techniques and methods for notched specimens in order to detect processes occurring in the notch base during the fatigue process and to provide input variables for the newly developed LPV.

DFG STA 1133/28-1

• In-situ and ex-situ characterisation of microstructure evolution in the scanning electron microscope for the development of microstructure models using copper as a model material

Understanding the microstructure evolution under quasi-static and cyclic loading of metallic materials is a central issue when it comes to coupling the mechanisms taking place in the material with the signal changes recorded using various measurement techniques. On the one hand, this provides a more fundamental understanding of the development of damage and, on the other hand, this information can be used as input variables in microstructure simulation models, which ideally allows a generally valid understanding of the development of damage to be established that can be transferred to other materials. The basic idea of this project is to link the changes in measured variable signals with material mechanisms and to develop a comprehensive understanding of them.

In particular, a scanning electron microscope (SEM; INST 252/27-1) procured through the HAW large-scale equipment programme will be used to record microstructural changes in the model material copper in interrupted tensile and fatigue tests and to make these usable for simulation approaches. In this approach, the results from tests with a tensile-compression module in the SEM are to be supplemented, which is expected to provide a profound understanding of the material mechanisms involved.

DFG STA 1133/26-1

• Evaluation of the application potential of non-destructive measurement methods for the characterisation of cyclic deformation behaviour in high-frequency fatigue tests

Within the scope of this research project, the application potential of various measurement methods (thermometry: IR camera, thermistors, thermocouples; resistometry: direct current measurement) during high-frequency fatigue tests on a resonance pulsator (MIKROTRON, Russenberger, INST 252/21-1) is to be tested and validated using the example of the quenched and tempered steel 42CrMo4. In addition to the general applicability, the aim is to quantify which measurement technique can detect the fatigue processes taking place with the best possible resolution and selectivity. In order to be able to consider the widest possible range of influencing factors in the project, a total of three important influencing parameters are systematically considered in the investigations. In addition to the influence of frequency, which will be demonstrated at three frequencies, the influence of specimen size and the influence of notches will also be considered. Due to the planned investigations on different specimen geometries, a possible heating of the specimen and thus a superimposition with the service life extension due to an increased measuring frequency is considered. In particular, the differentiation between notched and unnotched specimens is of great technical importance. The application of non-destructive exam methods to notched specimens enables the data obtained to be transferred to new fatigue life prediction methods and thus represents an important step towards accelerated determination of component Wöhler curves.

DFG STA 1133/25-1

• Development of a short-term method for the evaluation of damage-relevant parameters of ferritic materials and components used in nuclear technology "EKusaP

The aim of the research project “EKusaP” is to develop a short-time procedure to assess the fatigue behaviour of materials, taking relevant influencing parameters such as surface roughness and residual stresses into account. A total of five surface conditions are tested at three different temperatures and evaluated using the StressLife method. By integrating the parameters into the lifetime-prediction method, it should be possible to convert the S-N curves of different roughness and residual stress states into each other.

BMUV 1501623, Project Management Organisation GRS

• Micromagnetic in-situ detection of the microstructural evolution of fatigue-stressed steels of nuclear components for a short-time method for fatigue life prediction

The overall objective of the joint research project is the identification and qualification of micromagnetic measurands for a multi-parameter approach that is suitable for making a defined statement on the microstructural degradation of fatigued metallic nuclear power plant components. The project is intended to make a decisive contribution to the further development of methods for fatigue life prediction for nuclear components through the microstructural interpretation of micromagnetic measurands.

BMUV, Project Management Organisation GRS, cooperation project with WPT, TU Dortmund, GRS Cologne

• Micro- and nanostructured hard magnetic materials and components for microtechnical applications "MiNaMag" 

The limited availability of rare earth metals has increased the pressure to search for alternative, rare earth-free magnetic materials as well as for process-technological possibilities to induce the necessary magnetic anisotropy. Electrochemical deposition with an external current source ("electroplating") from aqueous solutions is to be used as the manufacturing process for the materials and components. This is a scalable, integrable and, in principle, simple, i.e. also cost-effective process, which, in conjunction with known and industrially used structuring processes such as lithography, permits arbitrary 2.5D geometries even with relatively thick layer heights. This results in nanocrystalline materials that have specific magnetic properties depending on their composition and material structure. By specifically influencing the nanoscale grains and nanostructuring (nanowires), the materials are to be adjusted to specific applications with regard to their magnetic properties in conjunction with the microstructuring of the components.

BMBF 13FH099KX0, Cooperation with Prof. Monika Saumer and Prof. Sven Urschel

• Use of the electrochemical potential to characterize the surface damage behavior of cyclically stressed materials

As part of the research project, a corrosion measuring station will be set up and integrated into a fatigue testing system (fatigue testing system) so that electrochemical investigations can be carried out. By exposing the materials to various non-corrosive and corrosive media (e.g. distilled water, acids, etc.), the medium-material interface reaction can be recorded in the form of the corrosion potential and current. In further investigations, impedance measurements are also to be carried out as an additional source of information for the investigation of the processes at the interface. In the project phase applied for, the aspect of non-corrosive media on austenitic materials (X6CrNiTi1810) is to be considered first.

BFI University of Applied Sciences Kaiserslautern, Cooperation mit Prof. Monika Saumer

• Use of Kerr microscopy to characterise the damage development in steels

The aim of the project is to transfer the methods and findings of Kerr microscopy from the model materials considered to date to ferritic-pearlitic and high-alloy austenitic steels, which are characterised by a multiphase structure. The aim is to gain new insights which, on the one hand, have not yet been adequately described in the literature and, on the other hand, provide a completely new understanding of the mechanisms taking place in the material.

BFI University of Applied Sciences Kaiserslautern

• Eddy current imaging with a vibrating probe for materials science applications

The project aims to develop a novel magnetic imaging technology called Vibrating Magnetic Tip Imaging (VMTI). This method promises a significant improvement in spatial resolution and differentiation of material properties such as electrical conductivity and magnetic permeability compared to conventional eddy current testing and magnetic force microscopy.

BFI University of Applied Sciences Kaiserslautern