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D02 - High-Speed Hardness Measurements of Metallic Materials

D02 - Hardness Measurements

Hardness measurements are performed to evaluate the resistance of solid materials against shape changes when compressive forces are applied. Standard specimens are pushed under a defined force into a test material to create a hardness indentation. In order to measure the hardness, the resulting indentation area or depth is measured. Within the subproject „Laser‑Härte“ of the CRC 1232 a new high-speed hardness measurement process based on laser induced shock waves is supposed to be established with a time for the hardness indentation and measurement procedure of less than one second. Especially, laser systems offer in the micro range the potential for the realisation of a measurement system with high flexibility and dynamic.

In comparison with other conventional measuring processes, plasma is created on a material surface with a pulsed TEA-CO2 Laser and results in a shock wave which pushes a standard specimen inside the test material. The accuracy of the positioning system between standard specimen, laser beam and test material surface has to be very high to achieve this goal. The process parameters are identified with the highest influence on the hardness indentation on the tested material surface. Further investigations aim to understand related process characteristics such as tested material, specimen geometry or surface integrity to be able to exactly evaluate and control the laser-induced shock waves. Hereby, the essential point of the subproject – the attainment of a method to receive reproducible values – is supposed to be achieved. Thus, the main aim of the subproject is to obtain a thorough understanding of laser shock processes to reach a high reproducibility as well as a fast analysis of the process characteristics to harness these as measurement method.

The subproject is part of the process chain within the CRC 1232 and accordingly, cooperates closely with other subprojects. The gained information of the measurements is given as early as possible to the corresponding subprojects. Primarily, specimen preparation is discussed and planed with the subproject P04. Subsequently, different indentation geometries and materials are analysed as well as correlated with material properties with the subproject P02. Together with subproject U04 the mechanisms of hardness indentations are investigated. In further phases of the subproject the measurement technique is supposed to be established as an automatic and high-throughput process. For this purpose, a system will be designed, whereby in-situ measurements are possible during the indentation process. Accordingly, the movement of the indenter can be related to the indentation geometry to determine further suitable descriptors and derive corresponding material properties.

 

Publications

T. Czotscher, D. Otero Baguer, F. Vollertsen, I. Piotrowska-Kurczewski, P. Maaß: Connection between shock wave induced indentations and hardness by means of neural networks. AIP Conf Proc 2113 (2019) 1–6 . [Link zum PDF]

T. Czotscher, N. Wielki, K. Vetter, F. Vollertsen, D. Meyer: Rapid Material Characterisation of Deep-alloyed Steels by Shock Wave Based Indentation Technique and Deep Rolling. Nanomanufacturing and Metrology (2019). [Link zum PDF]

T. Czotscher: Material Characterisation by New Indentation Technique Based on Laser-Induced Shockwaves, Lasers in Manufacturing and Materials Processing (2018) 1-19 (online). [Link zum PDF]

T. Czotscher: Analysis of TEA-CO2-laser induced plasma to establish a new measurement technique, Journal of Laser Applications 30, 3 (2018) 032604-1-5. [Link zum PDF]

C. Mittelstädt, N. Blanke, T. Czotscher, H. Freiße, C. Halisch, V. Schultz, A. Simic, A. Stephen, D. Tyralla, K. Vetter, R.B. Bergmann: Aktuelle Forschungsthemen zum Laserstrahleinsatz, Schweißen und Schneiden 70, 9 (2018) 650-657. [Link zum Beitrag]

T. Czotscher: Umformen, Fügen, Schneiden und Messen mit nur einem Laser - die abtragsfreie Laserschockbearbeitung, Laser Magazin 4 (2017) 6-8. [Link zum PDF]

T. Czotscher, S. Veenaas, F. Vollertsen: Possibilites to characterise laser induced shockwaves, Journal for Technology of Plasticity 42, 1 (2017) 1-7.

T. Czotscher, T. Wünderlich: Energy of Laser Induced Shockwaves, Proc. of the 5th Intern. Conf. on New Forming Technology (ICNFT 2018 ) MATEC Web of Conferences 190, 02006 (2018) [Link zum PDF]

T. Czotscher, F. Vollertsen: Plasma Induced On Indenter Balls, Proc. of the 8th International Conference on High Speed Forming, Columbus OH/USA (ICHSF 2018). [Link zum PDF]
 
T. Czotscher: Influence of focal position on laser-induced plasma and hardness indentations, Proc. of the 36th Intern. Congress on Applications of Laser & Electro-Optics (ICALEO 2017) Atlanta GA USA (2017) paper no. M903. [Link zur Konferenz]

T. Czotscher, F. Vollertsen: Process stability of laser induced plasma for hardness measurements Lasers in Manufacturing (LIM17) eds.: L. Overmeyer, U. Reisgen, A. Ostendorf, M. Schmidt (2017). [Link zum PDF]

Head


Prof.Dr.-Ing. Frank Vollertsen
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Project Management


Tobias Czotscher
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