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Licensed Unlicensed Requires Authentication Published by De Gruyter December 31, 2021

In situ Investigation during Low Pressure Carburizing by Means of Synchrotron X-ray Diffraction*

In-situ-Untersuchung während der Niederdruckaufkohlung mittels Synchrotron-Röntgenbeugung
O. B. Tapar, M. Steinbacher, J. Gibmeier, N. Schell and J. Epp

Abstract

In situ X-ray diffraction investigations during low pressure carburizing (LPC) processes were performed with a specially developed process chamber at the German Electron Synchrotron Facility (DESY) in Hamburg, Germany. Carbon saturation in austenite was reached in less than 20 seconds for all processes with different parameters and carbides formed at the surface. Therefore, the direct contribution of carbon donor gas to the carbon profile after 20 seconds was reduced to very low levels. After that point, further supply of carbon donor gas increased the amount of carbides formed at the surface, which will contribute to the carbon profile indirectly by dissolution in the following diffusion steps. During quenching, martensite at higher temperatures had a lower c/a ratio than later formed ones. This difference is credited to self-tempering effects and reordering of carbon atoms within the martensite lattice.

Kurzfassung

In-situ-Röntgenbeugungsuntersuchungen während des Niederdruckaufkohlungsprozesses wurden mit einer speziell entwickelten Prozesskammer am Deutschen Elektronen-Synchrotron (DESY) in Hamburg, Deutschland, durchgeführt. Die Kohlenstoffsättigung im Austenit wurde bei allen Prozessen mit unterschiedlichen Parametern in weniger als 20 Sekunden erreicht und Karbide bildeten sich an der Oberfläche. Daher war der direkte Beitrag des Kohlenstoffspendergases zum Kohlenstoffprofil nach 20 Sekunden auf ein sehr niedriges Niveau reduziert. Nach diesem Zeitpunkt erhöhte die weitere Zufuhr von Kohlenstoffspendergas die Menge der an der Oberfläche gebildeten Karbide, die in den folgenden Diffusionsschritten indirekt durch Auflösung zum Kohlenstoffprofil beitragen. Während des Abschreckens wiesen Martensite bei höheren Temperaturen ein niedrigeres c/a-Verhältnis auf als später gebildete Martensite. Dieser Unterschied wird auf Selbstanlasseffekte und auf eine Umordnung der Kohlenstoffatome im martensitischen Gitter zurückgeführt.


* Reworked version of a lecture held at ECHT – Quenching and Distortion Engineering QDE 2021, 26.-18. April 2021, online


Acknowledgement

The authors gratefully acknowledge the support from the Deutsche Forschungsgemeinschaft (DFG) for funding this research under the collaborative project EP-128/2-1- | GI-376/15-1 (DFG project no. 399551201), Deutsches Elektronen-Synchrotron (DESY) for granting beam time. Furthermore, the authors would like to thank Alexander Kohl and Sebastian Ohneseit for their participation in the measuring campaign at DESY and in particular Alexander Kohl for his engagement in the planning and realization of the process chamber.

Danksagung

Die Autoren bedanken sich bei der Deutschen Forschungsgemeinschaft (DFG) für die Förderung dieser Forschungsarbeit im Rahmen des Verbundprojekts EP-128/2-1- | GI-376/15-1 (DFG-Projekt Nr. 399551201) und beim Deutschen Elektronen-Synchrotron (DESY) für die Bereitstellung von Strahlzeit. Darüber hinaus danken die Autoren Alexander Kohl und Sebastian Ohneseit für ihre Teilnahme an der Messkampagne bei DESY und insbesondere Alexander Kohl für sein Engagement bei der Planung und Realisierung der Prozesskammer.

References

1 Clausen, B.; Hoffmann, E.; Zoch, H. W.: Beeinflussung der Randschicht durch die Einsatzhärtung. HTM J. Heat Treat. Mater. 63 (2008) 6, pp. 326–336, DOI:10.3139/105.10047310.3139/105.100473Search in Google Scholar

2 v. Starck, A.; Mühlbauer, A.; Kramer, C.: Handbook of Thermoprocessing Technologies: Fundamentals, Processes, Components, Safety. Vulkan-Verlag GmbH, Essen, 2005, pp. 509. – ISBN: 3802729331Search in Google Scholar

3 Altena, H.; Schrank, F.: Low Pressure Carburizing with High Pressure Gas Quenching. Gear Technol. Heat Treating 21 (2004) 2, pp. 27–32Search in Google Scholar

4 Edenhofer, B.: An overview of advances in atmosphere and vacuum heat treatment. Heat Treat. Met. 26 (1999) 1, pp. 1–5Search in Google Scholar

5 Gräfen, W.; Edenhofer, B.: New developments in thermo-chemical diffusion processes. Surf. Coatings Technol. 200 (2005) 5–6, pp. 1830–1836, DOI:10.1016/ j.surfcoat.2005.08.10710.1016/j.surfcoat.2005.08.107Search in Google Scholar

6 Kula, P.; Pietrasik, R.; Dybowski, K.: Vacuum carburizing – Process optimization. J. Mater. Process. Technol. 164–165 (2005) 2, pp. 876–881, DOI:10.1016/j. jmatprotec.2005.02.14510.1016/j.jmatprotec.2005.02.145Search in Google Scholar

7 Prunel, G.; Stauder, B.: Advantages of low pressure carburizing in the heat treatment. Transactions Mater. Heat Treat. 25 (2004) 5, pp. 364–369Search in Google Scholar

8 Tapar, O. B.; Epp, J.; Steinbacher, M.; Gibmeier, J.: In-situ synchrotron X-ray diffraction investigation of microstructural evolutions during low pressure carburizing. Metall. Mater. Trans. A Phys. Metall. Mater. Sci. 52 (2021) 4, pp. 1–16, DOI:10.1007/s11661-021-06171-210.1007/s11661-021-06171-2Search in Google Scholar

9 Ashiotis, G.; Deschildre, A.; Nawaz, Z.; Wright, J. P.; Karkoulis, D.; Picca, F. E.; Kieffer, J.: The fast azimuthal integration Python library: PyFAI. J. Appl. Crystallogr. 48 (2015) 2, pp. 510–519, DOI:10.1107/S160057671500430610.1107/S1600576715004306Search in Google Scholar

10 Coelho, A. A.: TOPAS and TOPAS-Academic: An optimization program integrating computer algebra and crystallographic objects written in C++: An. J. Appl. Crystallogr. 51 (2018) 1, pp. 210–218, DOI:10.1107/S160057671800018310.1107/S1600576718000183Search in Google Scholar

11 Onink, M.; Brakman, C. M.; Tichelaar, F. D.; Mittemeijer, E. J.; van der Zwaag, S.; Root, J. H.; Konyer, N. B.: The lattice parameters of austenite and ferrite in FeC alloys as functions of carbon concentration and temperature. Scr. Metall. Mater. 29 (1993) 8, pp. 1011–1016, DOI:10.1016/0956-716X(93)90169-S10.1016/0956-716X(93)90169-SSearch in Google Scholar

12 Esper, B.: Acetylene: The Right Carbon Source For Low-Pressure Carburizing. Ind. Heat. 76 (2009) 11, pp. 45–47Search in Google Scholar

13 Steinbacher, M.: Thermogravimetrische Messungen beim Niederdruckaufkohlen als Grundlage für Simulationen. Dissertation, Universität Bremen, 2012Search in Google Scholar

14 Herring, D. H.; Peters Jr., R. V.: New-Formula Acetylene Cool for Heat Treatment. Gear Technol. 30 (2013) 6, pp. 90–94Search in Google Scholar

15 Madix, R. J.: Reaction Kinetics and Mechanism on Metal Single Crystal Surfaces. Adv. Catal. 29 (1980) pp. 1–53, DOI:10.1016/S0360-0564(08)60119-410.1016/S0360-0564(08)60119-4Search in Google Scholar

16 Neubauer, R.; Whelan, C. M.; Denecke, R.; Steinrück, H. P.: The thermal chemistry of saturated layers of acetylene and ethylene on Ni(100) studied by in situ synchrotron x-ray photoelectron spectroscopy. J. Chem. Phys. 119 (2003) 3, pp. 1710–1718, DOI:10.1063/1.158243210.1063/1.1582432Search in Google Scholar

17 Bhadeshia, H. K. D. H.; Honeycombe, R. W. K.: Steels: Microstructure and Properties. 4. Ed., Elsevier Inc, Amsterdam, 2017, pp. 14210.1016/B978-0-08-100270-4.00013-5Search in Google Scholar

18 Lu, Y.; Yu, H.; Sisson, R. D.: The effect of carbon content on the c/a ratio of asquenched martensite in Fe-C alloys. Mater. Sci. Eng. A. 700 (2017) pp. 592–597, DOI:10.1016/j.msea.2017.05.09410.1016/j.msea.2017.05.094Search in Google Scholar

19 Epp, J.: Time Resolved Investigations Of Phase Transformations and Stress During Heat Treatments of Steel Samples by Meams of Diffraction Experiments. Dissertation, Universität Bremen, 2016, DOI:10.2370/978384404547510.2370/9783844045475Search in Google Scholar

20 Bhadeshia, H. K. D. H.: Carbon content of retained austenite in quenched steels. Met. Sci. 17 (1983) 3, pp. 1–2, DOI:10.1179/03063458379042108710.1179/030634583790421087Search in Google Scholar

21 Lerchbacher, C.; Zinner, S.; Leitner, H.: Atom probe study of the carbon distribution in a hardened martensitic hot-work tool steel X38CrMoV5-1. Micron. 43 (2012) 7, pp. 818–826, DOI:10.1016/j.micron.2012.02.00510.1016/j.micron.2012.02.005Search in Google Scholar

22 Sarikaya, M.; Thomas, G.; Steeds, J. W.; Barnard, S. J.; Smith, G. D. W.: Solute Element Partitioning and Austenite Stabilization in Steels, Technical Report, Lawrence Berkeley Lab, Berkeley, USA, 1982, DOI:10.2172/703196110.2172/7031961Search in Google Scholar

23 Sherman, D. H.; Cross, S. M.; Kim, S.; Grandjean, F.; Long, G. J.; Miller, M. K.: Characterization of the carbon and retained austenite distributions in martensitic medium carbon, high silicon steel. Metall. Mater. Trans. A Phys. Metall. Mater. Sci. 38 (2007) 8, pp. 1698–1711, DOI:10.1007/s11661-007-9160-310.1007/s11661-007-9160-3Search in Google Scholar

24 Thomson, R. C.; Miller, M. K.: An atom probe study of carbon distribution in martensite in 2 1/4 Cr1Mo steel. Scr. Metall. Mater. 32 (1995) 2, pp. 149–154, DOI:10.1016/S0956-716X(99)80028-410.1016/S0956-716X(99)80028-4Search in Google Scholar

25 Morsdorf, L.; Tasan, C. C.; Ponge, D.; Raabe, D.: 3D structural and atomic-scale analysis of lath martensite: Effect of the transformation sequence. Acta Mater. 95 (2015) pp. 366–377, DOI:10.1016/j.actamat.2015.05.02310.1016/j.actamat.2015.05.023Search in Google Scholar

26 Wilde, J.; Cerezo, A.; Smith, G. D. W.: Three-dimensional atomic-scale mapping of a Cottrell atmosphere around a dislocation in iron. Scr. Mater. 43 (2000) 1, pp. 39–48, DOI:10.1016/S1359-6462(00)00361-410.1016/S1359-6462(00)00361-4Search in Google Scholar

27 Zhu, C.; Cerezo, A.; Smith, G. D. W.: Carbide characterization in low-temperature tempered steels. Ultramicroscopy. 109 (2009) 5, pp. 545–552, DOI:10.1016/j. ultramic.2008.12.00710.1016/j.ultramic.2008.12.007Search in Google Scholar

Published Online: 2021-12-31

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