--- _id: '62024' abstract: - lang: eng text: "Abstract\r\n This paper presents a characterization of the microstructural evolution and its correlation with the magnetic structure due to flow forming of semi-finished tubes of austenitic stainless steel AISI 304L. The plastic deformation triggers a phase transformation of the metastable austenite into α’-martensite.\r\n Depending on the combination of production parameters, different fractions of strain-induced α’-martensite were measured by means non-destructive micromagnetic techniques and correlated with the evolution of hardness and the microstructure using electron backscatter diffraction analyses. The magneto-optical Kerr effect analysis was used as a tool to perform a qualitative analysis of the evolution of the magnetic domain structure correlated with the formation of α’-martensite. An analysis of these data allowed to derive surface magnetization hysteresis loops that were compared with integral hysteresis loops of the specimens. It was proven by both methods that the formation of martensite increases the magnetic energy and the spontaneous magnetization of the specimens. The results of this investigation contribute to a better understanding of micromagnetic sensors to monitor and control the formation of α’-martensite in a flow forming. Furthermore, various techniques have demonstrated the evolution of the magnetic properties of the material, which can be applied in applications for invisible coding of workpieces." author: - first_name: Julian full_name: Rozo Vasquez, Julian last_name: Rozo Vasquez - first_name: Jan full_name: Tappe, Jan last_name: Tappe - first_name: Bahman full_name: Arian, Bahman id: '36287' last_name: Arian - first_name: Lukas full_name: Kersting, Lukas last_name: Kersting - first_name: Werner full_name: Homberg, Werner id: '233' last_name: Homberg - first_name: Ansgar full_name: Trächtler, Ansgar id: '552' last_name: Trächtler - first_name: Frank full_name: Walther, Frank last_name: Walther citation: ama: Rozo Vasquez J, Tappe J, Arian B, et al. Magneto-optical Kerr effect analysis of strain-induced martensite formation during flow forming of metastable austenitic steel AISI 304L. Practical Metallography. 2025;62(9-10):617-633. doi:10.1515/pm-2025-0059 apa: Rozo Vasquez, J., Tappe, J., Arian, B., Kersting, L., Homberg, W., Trächtler, A., & Walther, F. (2025). Magneto-optical Kerr effect analysis of strain-induced martensite formation during flow forming of metastable austenitic steel AISI 304L. Practical Metallography, 62(9–10), 617–633. https://doi.org/10.1515/pm-2025-0059 bibtex: '@article{Rozo Vasquez_Tappe_Arian_Kersting_Homberg_Trächtler_Walther_2025, title={Magneto-optical Kerr effect analysis of strain-induced martensite formation during flow forming of metastable austenitic steel AISI 304L}, volume={62}, DOI={10.1515/pm-2025-0059}, number={9–10}, journal={Practical Metallography}, publisher={Walter de Gruyter GmbH}, author={Rozo Vasquez, Julian and Tappe, Jan and Arian, Bahman and Kersting, Lukas and Homberg, Werner and Trächtler, Ansgar and Walther, Frank}, year={2025}, pages={617–633} }' chicago: 'Rozo Vasquez, Julian, Jan Tappe, Bahman Arian, Lukas Kersting, Werner Homberg, Ansgar Trächtler, and Frank Walther. “Magneto-Optical Kerr Effect Analysis of Strain-Induced Martensite Formation during Flow Forming of Metastable Austenitic Steel AISI 304L.” Practical Metallography 62, no. 9–10 (2025): 617–33. https://doi.org/10.1515/pm-2025-0059.' ieee: 'J. Rozo Vasquez et al., “Magneto-optical Kerr effect analysis of strain-induced martensite formation during flow forming of metastable austenitic steel AISI 304L,” Practical Metallography, vol. 62, no. 9–10, pp. 617–633, 2025, doi: 10.1515/pm-2025-0059.' mla: Rozo Vasquez, Julian, et al. “Magneto-Optical Kerr Effect Analysis of Strain-Induced Martensite Formation during Flow Forming of Metastable Austenitic Steel AISI 304L.” Practical Metallography, vol. 62, no. 9–10, Walter de Gruyter GmbH, 2025, pp. 617–33, doi:10.1515/pm-2025-0059. short: J. Rozo Vasquez, J. Tappe, B. Arian, L. Kersting, W. Homberg, A. Trächtler, F. Walther, Practical Metallography 62 (2025) 617–633. date_created: 2025-10-30T12:22:54Z date_updated: 2025-10-30T12:54:17Z department: - _id: '153' - _id: '241' - _id: '156' doi: 10.1515/pm-2025-0059 intvolume: ' 62' issue: 9-10 language: - iso: eng main_file_link: - open_access: '1' url: https://doi.org/10.1515/pm-2025-0059 oa: '1' page: 617-633 publication: Practical Metallography publication_identifier: issn: - 2195-8599 - 0032-678X publication_status: published publisher: Walter de Gruyter GmbH status: public title: Magneto-optical Kerr effect analysis of strain-induced martensite formation during flow forming of metastable austenitic steel AISI 304L type: journal_article user_id: '82875' volume: 62 year: '2025' ... --- _id: '33694' abstract: - lang: eng text: "Abstract\r\n The round robin test investigated the reliability users can expect for AlSi10Mg additive manufactured specimens by laser powder bed fusion through examining powder quality, process parameter, microstructure defects, strength and fatigue. Besides for one outlier, expected static material properties could be found. Optical microstructure inspection was beneficial to determine true porosity and porosity types to explain the occurring scatter in properties. Fractographic analyses reveal that the fatigue crack propagation starts at the rough as-built surface for all specimens. Statistical analysis of the scatter in fatigue using statistical derived safety factors concludes that at a stress of 36.87 MPa the fatigue limit of 107 cycles could be reached for all specimen with a survival probability of 99.999 %." author: - first_name: M. full_name: Schneider, M. last_name: Schneider - first_name: D. full_name: Bettge, D. last_name: Bettge - first_name: M. full_name: Binder, M. last_name: Binder - first_name: K. full_name: Dollmeier, K. last_name: Dollmeier - first_name: Malte full_name: Dreyer, Malte id: '66695' last_name: Dreyer orcid: 0000-0001-9560-9510 - first_name: K. full_name: Hilgenberg, K. last_name: Hilgenberg - first_name: B. full_name: Klöden, B. last_name: Klöden - first_name: T. full_name: Schlingmann, T. last_name: Schlingmann - first_name: J. full_name: Schmidt, J. last_name: Schmidt citation: ama: 'Schneider M, Bettge D, Binder M, et al. Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy. Practical Metallography. 2022;59(10):580-614. doi:10.1515/pm-2022-1018' apa: 'Schneider, M., Bettge, D., Binder, M., Dollmeier, K., Dreyer, M., Hilgenberg, K., Klöden, B., Schlingmann, T., & Schmidt, J. (2022). Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy. Practical Metallography, 59(10), 580–614. https://doi.org/10.1515/pm-2022-1018' bibtex: '@article{Schneider_Bettge_Binder_Dollmeier_Dreyer_Hilgenberg_Klöden_Schlingmann_Schmidt_2022, title={Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy}, volume={59}, DOI={10.1515/pm-2022-1018}, number={10}, journal={Practical Metallography}, publisher={Walter de Gruyter GmbH}, author={Schneider, M. and Bettge, D. and Binder, M. and Dollmeier, K. and Dreyer, Malte and Hilgenberg, K. and Klöden, B. and Schlingmann, T. and Schmidt, J.}, year={2022}, pages={580–614} }' chicago: 'Schneider, M., D. Bettge, M. Binder, K. Dollmeier, Malte Dreyer, K. Hilgenberg, B. Klöden, T. Schlingmann, and J. Schmidt. “Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy.” Practical Metallography 59, no. 10 (2022): 580–614. https://doi.org/10.1515/pm-2022-1018.' ieee: 'M. Schneider et al., “Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy,” Practical Metallography, vol. 59, no. 10, pp. 580–614, 2022, doi: 10.1515/pm-2022-1018.' mla: 'Schneider, M., et al. “Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy.” Practical Metallography, vol. 59, no. 10, Walter de Gruyter GmbH, 2022, pp. 580–614, doi:10.1515/pm-2022-1018.' short: M. Schneider, D. Bettge, M. Binder, K. Dollmeier, M. Dreyer, K. Hilgenberg, B. Klöden, T. Schlingmann, J. Schmidt, Practical Metallography 59 (2022) 580–614. date_created: 2022-10-11T13:15:48Z date_updated: 2023-01-04T14:48:17Z doi: 10.1515/pm-2022-1018 intvolume: ' 59' issue: '10' keyword: - Metals and Alloys - Mechanics of Materials - Condensed Matter Physics - Electronic - Optical and Magnetic Materials language: - iso: eng page: 580-614 publication: Practical Metallography publication_identifier: issn: - 2195-8599 - 0032-678X publication_status: published publisher: Walter de Gruyter GmbH status: public title: 'Reproducibility and Scattering in Additive Manufacturing: Results from a Round Robin on PBF-LB/M AlSi10Mg Alloy' type: journal_article user_id: '66695' volume: 59 year: '2022' ... --- _id: '34000' abstract: - lang: eng text: "Abstract\r\n This paper presents the characterization of the microstructure evolution during flow forming of austenitic stainless steel AISI 304L. Due to plastic deformation of metastable austenitic steel, phase transformation from γ-austenite into α’-martensite occurs. This is initiated by the formation of shear bands as product of the external stresses. By means of coupled microscopic and micromagnetic investigations, a characterization of the microstructure was carried out. In particular, this study shows the distribution of the strain-induced α’-martensite and its influence on material properties like hardness at different depths. The microstructural analyses by means of electron backscattered diffraction (EBSD) technique, evidence a higher amount of α’-martensite (ca. 23 %) close to the outer specimen surface, where the plastic deformation and the direct contact with the forming tool take place. In the middle area (ca. 1.5 mm depth from the outer surface), the portion of transformed α’-martensite drops to 7 % and in the inner surface to 2 %. These results are well correlated with microhardness and micromagnetic measurements at different depths. EBSD and atomic force microscopy (AFM) were used to make a detailed characterization of the topography and degree of deformation of the shear bands. Likewise, the mechanisms of nucleation of α’-martensite were discussed. This research contributes to the development of micromagnetic sensors to monitor the evolution of properties during flow forming. This makes them more suitable for closed-loop property control, which offers possibilities for an application-oriented and more efficient production." author: - first_name: Julian full_name: Rozo Vasquez, Julian last_name: Rozo Vasquez - first_name: Hanigah full_name: Kanagarajah, Hanigah last_name: Kanagarajah - first_name: Bahman full_name: Arian, Bahman id: '36287' last_name: Arian - first_name: Lukas full_name: Kersting, Lukas last_name: Kersting - first_name: Werner full_name: Homberg, Werner id: '233' last_name: Homberg - first_name: Ansgar full_name: Trächtler, Ansgar id: '552' last_name: Trächtler - first_name: Frank full_name: Walther, Frank last_name: Walther citation: ama: Rozo Vasquez J, Kanagarajah H, Arian B, et al. Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming. Practical Metallography. 2022;59(11):660-675. doi:10.1515/pm-2022-0064 apa: Rozo Vasquez, J., Kanagarajah, H., Arian, B., Kersting, L., Homberg, W., Trächtler, A., & Walther, F. (2022). Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming. Practical Metallography, 59(11), 660–675. https://doi.org/10.1515/pm-2022-0064 bibtex: '@article{Rozo Vasquez_Kanagarajah_Arian_Kersting_Homberg_Trächtler_Walther_2022, title={Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming}, volume={59}, DOI={10.1515/pm-2022-0064}, number={11}, journal={Practical Metallography}, publisher={Walter de Gruyter GmbH}, author={Rozo Vasquez, Julian and Kanagarajah, Hanigah and Arian, Bahman and Kersting, Lukas and Homberg, Werner and Trächtler, Ansgar and Walther, Frank}, year={2022}, pages={660–675} }' chicago: 'Rozo Vasquez, Julian, Hanigah Kanagarajah, Bahman Arian, Lukas Kersting, Werner Homberg, Ansgar Trächtler, and Frank Walther. “Coupled Microscopic and Micromagnetic Depth-Specific Analysis of Plastic Deformation and Phase Transformation of Metastable Austenitic Steel AISI 304L by Flow Forming.” Practical Metallography 59, no. 11 (2022): 660–75. https://doi.org/10.1515/pm-2022-0064.' ieee: 'J. Rozo Vasquez et al., “Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming,” Practical Metallography, vol. 59, no. 11, pp. 660–675, 2022, doi: 10.1515/pm-2022-0064.' mla: Rozo Vasquez, Julian, et al. “Coupled Microscopic and Micromagnetic Depth-Specific Analysis of Plastic Deformation and Phase Transformation of Metastable Austenitic Steel AISI 304L by Flow Forming.” Practical Metallography, vol. 59, no. 11, Walter de Gruyter GmbH, 2022, pp. 660–75, doi:10.1515/pm-2022-0064. short: J. Rozo Vasquez, H. Kanagarajah, B. Arian, L. Kersting, W. Homberg, A. Trächtler, F. Walther, Practical Metallography 59 (2022) 660–675. date_created: 2022-11-04T08:29:21Z date_updated: 2023-05-02T08:19:27Z department: - _id: '156' - _id: '153' - _id: '241' doi: 10.1515/pm-2022-0064 intvolume: ' 59' issue: '11' keyword: - Metals and Alloys - Mechanics of Materials - Condensed Matter Physics - Electronic - Optical and Magnetic Materials language: - iso: eng page: 660-675 publication: Practical Metallography publication_identifier: issn: - 2195-8599 - 0032-678X publication_status: published publisher: Walter de Gruyter GmbH quality_controlled: '1' status: public title: Coupled microscopic and micromagnetic depth-specific analysis of plastic deformation and phase transformation of metastable austenitic steel AISI 304L by flow forming type: journal_article user_id: '36287' volume: 59 year: '2022' ...