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Steels

SPP 2086 – Surface Conditioning in Machining Processes

Duration: 2018 until 2021 Consortium: 23 Research Institutes Sponsor: Deutsche Forschungsgesellschaft (DFG)
SPP2086

The Priority Programme 2086 aims to provide dynamic control systems for the machining of metallic materials. In-process measurement techniques in combination with a deep understanding of the machining process form the basis for the design of a process control that allows the creation of defined geometries as well as the reliable conditioning of surface edge zones, regardless of any disturbance variable.

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Process-integrated measuring and control system for the determination and reliable generation of functionally relevant properties in surface edge zones during BTA deep-hole-drilling

Duration: 2018 until 2021 Project partner: Institut für spanende Fertigung
BTA-Tiefbohren

In this research project BTA deep-hole-drilling is being analysed by means of in-process measurement techniques. The project aims to examine the coherence between the design of the machining process and the properties in surface edge zones. The main criteria that are being employed to examine the conditioned surface edge zones, are residual stress, hardness and changes in microstructure. Based on the results of these studies, a dynamic control system will be developed that will allow a reliable conditioning of surfaces, so that surface edge zones with defined properties can be created, regardless of any disturbance variable.

For further information, please refer to:
M.Sc. Simon Strodick

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Quantitative evaluation and efficient characterization of intrinsic and extrinsic influences on cyclic properties of high-strength steels

Duration: 2019 until 2021 Project partner: iehk_en Sponsor: bmwi_logo
forschung5 forschung6
Source: Hirschvogel Automotive AG Group

For the reliable and economical use of brazed components under corrosive influence, the characterization of fatigue behaviour and the determination of lifetime is elementary. The aim of this project is to gain a fundamental understanding of the influence of the microstructure on fatigue and corrosion properties. For this purpose, brazed joints with different alloys and manufacturing parameters are produced at MEPhI University and characterized at WPT. Among others, multiple step tests in synthetic exhaust gas condensate, in-situ tensile tests in scanning electron microscope as well as fractographic investigations by 3D-EDX and 3D-EBSD analyses are used. The generated process-structure-property-relationship between the parameters are used to optimize the manufacturing process and to evaluate the influence of individual alloying elements.

For further information, please refer to:
M.Sc. Nikolas Baak

 


 

Alloying-dependent microstructure influence on corrosion fatigue mechanisms of brazed AISI 304/NiCrSiB joints

Duration: 2019 until 2021 Project partner: Logo der MEPhI Sponsor: Deutsche Forschungsgesellschaft (DFG)   rfbr2
Mikrostrukur Versuchsaufbau_180504

For the reliable and economical use of brazed components under corrosive influence, the characterization of fatigue behaviour and the determination of lifetime is elementary. The aim of this project is to gain a fundamental understanding of the influence of the microstructure on fatigue and corrosion properties. For this purpose, brazed joints with different alloys and manufacturing parameters are produced at MEPhI University and characterized at WPT. Among others, multiple step tests in synthetic exhaust gas condensate, in-situ tensile tests in scanning electron microscope as well as fractographic investigations by 3D-EDX and 3D-EBSD analyses are used. The generated process-structure-property-relationship between the parameters are used to optimize the manufacturing process and to evaluate the influence of individual alloying elements.

For further information, please refer to:
M.Sc. Johannes Otto

 


 

SPP 2013 – The utilization of residual stresses induced by metal forming

Duration: 2018 until 2021 Consortium: 25 Research Institutes Sponsor: Deutsche Forschungsgesellschaft (DFG)
SPP2013

In the Priority Programme 2013 scientific basics for potential applications of deformation-induced residual stresses will be developed. Residual stresses have a great influence on the performance of components produced by forming procedures. So far, they are considered as a factor to be avoided with a largely negative effect on the manufacturability and lifetime of components. The main objective of the Priority Programme is to control and tailor the amount and distribution of deformation-induced residual stresses, so that they have a positive influence on the relevant properties of the formed components.

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Selective induction and stabilization of residual stresses in austenitic disc springs by incremental forming and integrated surface layer treatment

Duration: 2018 until 2021 Project partner: Brandenburgische Technische Universität Cottbus-Senftenberg
Tellerfedern

Disc springs are required to meet high fatigue resistance demands during their operation. Their fatigue resistance is limited by the operational tensile stresses. An induction of compressive residual stresses within tensile loaded areas contributes to the extension of their fatigue resistance. The application of conventional methods, like shot peening, are time and cost-intensive. The main objective of this project is to integrate the adjustment of residual stresses within the forming process of the disc springs in order to improve their resistance properties. For this purpose, a deeper understanding of the residual stresses formation during the incremental forming and their stability under static and cyclic loading is required. Also, deformation-induced martensite formation in metastable austenitic spring steels and its effect on residual stresses has to be characterized in general. A fast and reliable method for a more effective process chain monitoring will be developed by correlating the micromagnetic measurements with conventionally recorded residual stresses. Finally, by correlation of the manufacturing parameters with the micromagnetic measurements and the mechanical testing results, a model for the targeted adjustment of the residual stresses will be developed and established.

For further information, please refer to:
M.Sc. Ramin Hajavifard

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TRR 188 – Damage Controlled Forming Processes

Duration: 2017 until 2020 Consortium: 3 Universities
1 Research Institute
Sponsor: Deutsche Forschungsgesellschaft (DFG)
TRR188

The CRC/Transregio 188 Damage Controlled Forming Processes is a joint long-term research project with participation of RWTH Aachen, BTU Cottbus-Senftenberg, TU Dortmund University and the Max-Planck-Institut für Eisenforschung. The overall objective is to investigate damage nucleation and evolution in hot and cold forming on multi-process and multi-scale level by merging of competences in the areas of forming technology (A-projects), materials science (B-projects) and mechanical material modeling (C-projects). Strategies are developed to permanently improve the performance of components produced by shaping technology by adjustment of damage profiles through optimization of load paths.

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B01 Measurement of interaction of ductile and cyclic damage mechanisms at macroscopic level

TRR188_B01

The purpose of the project is the development and validation of a short-time testing method based on instrumented uniaxial cyclic deformation tests of 16MnCrS5 and DP800 specimens, in order to evaluate the impact of ductile damage on the operating performance and fatigue life of cold- and hot-worked material. Due to the measurement of damage evolution on macroscopic scale, a fundamental insight into the interaction of single forming processes and load paths with regard to achievable material and component performance will be generated. The methods developed are utilized by the consortium for process analysis and calibration of newly developed material models in order to achieve the proposed advance in design and manufacturing of high-performance forming parts.

For further information, please refer to:
M.Sc. Lukas Lücker

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C01 Thermo-mechanical coupled damage model for operational loading conditions – predicting the operating time of formed components

42CroMo4_2 TRR188_C01_2

This project aims to predict the behavior of components made of 16MnCrS5 under operational loading conditions. Particularly, the influence of ductile initial damage caused by a previous forming process is analyzed. For that purpose, a novel characterization of microstructural defects is elaborated and combined with a novel thermo-mechanical coupled macroscopic constitutive. By doing so, even complex loading paths – including those characterized by axial-torsional loading – can be investigated in a first step. Subsequently, improved loading paths can be virtually designed.

For further information, please refer to:
M.Sc. Kerstin Möhring

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Microstructure-based understanding of the test frequency influence on the corrosion fatigue behaviour of austenite AISI 304L joints brazed with nickel based filler metal

Novel test systematics for the characterization of corrosion-fatigue-behaviour of brazing joints
Duration: 2015 until 2020 Sponsor: Deutsche Forschungsgesellschaft (DFG)
Darstellung einer Lötnaht

The operational behaviour of brazed constructions in exhaust gas carrying components is significantly influenced by the corrosion fatigue behaviour of the brazed joins. Within this research project, a mechanism-based characterisation of the test frequency influence on the corrosion fatigue properties of austenite joints, brazed with two nickel based filler metals, is planned. The aim is a microstructure-based understanding of the influence of the frequency- and time-dependent corrosion on the deformation and damage mechanisms. Furthermore, a damage model for a efficient characterization and prediction of the frequency- and time-dependant corrosions fatigue behaviour of brazed joints in exhaust gas condensate will be developed.

For further information, please refer to:
M.Sc. Anke Schmiedt-Kalenborn

 


 

Innovations for optimal use of weathering structural steel in steel and composite bridges

Duration: 2016 until 2019 Consortium: 2 Chairs
1 Industrial Enterprise
Sponsor: bmwi_logo
wetterfester_Baustahl_1wetterfester_Baustahl_2

The aim of the project is to create prerequisites for the optimum usage of weathering steel in steel and composite bridge constructions. The new inspection methods are to be developed for the reliable detection of cracks below the corrosion layer in weathering steel bridges during the entire service life of the bridge (100 years). Intended research results should provide secure, contactless measurement technology for damage analysis of weathering steel bridges.

For further information, please refer to:
Dr.-Ing. Marina Knyazeva

 


 

Microstructure based determination of maximum operation time for corrosion fatigue stressed materials and components of nuclear technology – MibaLeb

Duration: 2016 until 2019 Consortium: 3 Universities
1 Industrial Enterprise
Sponsor: Bundesministerium für Wirtschaft und Energie (BMWi)
Mibaleb Mibaleb2
Source: Allva Edelstahl

Safety-related parts and components from metastable austenitic steel, such as pipes in light water reactors of nuclear power plants, are subjected to certain operational thermal, mechanical and medial loads, which can reduce their lifetime considerably. The aim of the research project is a process-oriented analysis of different fatigue mechanisms by means of various non-destructive testing and electrochemical measurement techniques to develop a design concept for determining the maximum service life of fatigue and corrosion fatigue stressed materials and components.

For further information, please refer to:
M.Sc. Anke Schmiedt-Kalenborn
M.Sc. Ronja Scholz

 


 

Investigations on the influence of machining and sulphur content on the fatigue strength of the quenched and tempered steel 42CrMo4+QT

Duration: 2016 until 2018 Project partner: Institut für Spanende Fertigung Sponsor: Deutsche Forschungsgesellschaft (DFG)
42CroMo4_1 42CroMo4_2 42CroMo4_3
Source: Bosch

In this research project the influence of the surface edge zone resulting from deep hole drilling on the microstructure and the fatigue behaviour will be investigated using the example of the quenched and tempered steel 42CrMo4+QT. Different alloy compositions of steel with varying sulphur contents will be tested. The results will be employed to develop a model based correlation between the workpiece and cutting parameter dependence between edge zone and fatigue strength to extend the state of knowledge about surface edge zone influences by deep hole drilling and the resulting fatigue behaviour and to increase the lifetime of components. For a comparable characterisation of the fatigue behaviour, established tests of both destructive materials testing and new non-destructive tests will be conducted.

For further information, please refer to:
M.Sc. Nikolas Baak