Modern component designs aim to achieve optimal weight for efficiency without compromising reliability. This requires high-strength and defect-tolerant materials in many applications. Copper precipitates, for instance, can be used to improve the defect tolerance of steels by increasing their local hardening potential.

The central goal of this project was to determine the precipitation states of copper as a function of the carbon content and heat treatment conditions, and to describe the mechanisms that led to increased defect tolerance. Using cyclic indentation tests (PhyBaL_CHT), we identified heat treatment conditions for which a different defect tolerance could be expected due to the different precipitation states of Cu. When we characterized these variations, we found that the formation of Cu precipitates led to an increase of tensile and fatigue strength for all carbon contents investigated. For the low carbon content steels examined, we observed an improved defect tolerance with increasing cyclic hardening potential caused by the respective precipitation state of Cu.

This project is conducted in collaboration with the Steel Institute of RWTH Aachen University and financially supported by the German Research Foundation (DFG).

Further Information:

·         M.Sc. David Görzen

·         Dr.-Ing. Bastian Blinn

·         Prof. Dr.-Ing. T. Beck

B. Blinn, D. Görzen, M. Klein, D. Eifler, T. Beck:

PhyBaL_CHT – Influence of indentation force on the results of cyclic hardness tests and investigations of comparability to uniaxial fatigue loading,
International Journal of Fatigue 119, 2019, pp. 78-88

https://doi.org/10.1016/j.ijfatigue.2018.09.025

H. Schwich, D. Görzen, B. Blinn, W. Bleck T. Beck:

Characterization of the precipitation behavior and resulting mechanical properties of copper-alloyed ferritic steel,
Materials Science and Engineering: A 772, 2020, 138807

https://doi.org/10.1016/j.msea.2019.138807

D. Görzen, H. Schwich, B. Blinn, W. Bleck T. Beck:

Influence of different precipitation states of Cu on the quasi-static and cyclic deformation behavior of Cu alloyed steels with different carbon contents,
International Journal of Fatigue 136, 2020, 105587

https://doi.org/10.1016/j.ijfatigue.2020.105587

D. Görzen, H. Schwich, B. Blinn, W. Song, U. Krupp, W. Bleck, T. Beck:
Influence of Cu precipitates and C content on the defect tolerance of steels,
International Journal of Fatigue 144, 2020, 106042
https://doi.org/10.1016/j.ijfatigue.2020.106042