Experimental and Numerical Investigation of the Surface Layer Conditions after Carbonitriding of Powder Metallurgical Steels. Part 1: Diffusion in Components of Graded Porosity
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J. M. Damon
,
H. Surm
Abstract
Case hardening processes such as carbonitriding can be used to improve the performance of powder metallurgical structural components. Due to the amount of carbon and nitrogen introduced, it is possible to adjust the hardness and residual stress of the surface layer. Due to their porosity, powder metallurgical components show a significantly increased diffusivity and therefore increased demands on the process control. In order to be able to make a quantitative statement about the effects of diffusivity as a function of porosity, common densities of 6.9 g/cm3, 7.2 g/cm3and 7.35 g/cm3for PM-steel are examined in a total of ten process sequences. By means of simulative approaches, the resulting element depth profiles can be calculated and the surface layer condition can be predicted by a subsequent heat treatment simulation. In a two-part work, the mass transport during carbonitriding is investigated in the first part and the resulting surface layer conditions after heat treatment in the second part. By considering different process combinations and porosities, model approaches of volume and pore diffusion can be formulated and quantitative element depth profiles can be predicted and validated depending on the process parameters. ◼
Kurzfassung
Zur Verbesserung der Leistungsfähigkeit von pulvermetallurgischen Strukturbauteilen können Einsatzhärteverfahren wie das Carbonitrieren eingesetzt werden. Aufgrund der eingebrachten Menge von Kohlenstoff und Stickstoff können so gezielt Randschichtzustände bezüglich Härte und Eigenspannung eingestellt werden. Dabei weisen pulvermetallurgische Bauteile aufgrund ihrer Porosität eine deutlich erhöhte Diffusivität und folglich erhöhte Anforderungen an die Prozessführung auf. Um eine quantitative Aussage über die Auswirkungen der Diffusivität in Abhängigkeit der Porosität geben zu können, werden für PM-Stahl gängige Dichten von 6,9 g/cm3, 7,2 g/cm3und 7,35 g/cm3in insgesamt zehn Prozessführungen untersucht. Mittels simulativer Ansätze können die sich einstellenden Elementtiefenverläufe berechnet und durch eine nachgeschaltete Wärmebehandlungssimulation der Randschichtzustand vorhergesagt werden. In einer zweiteiligen Arbeit wird in diesem ersten Teil der Massentransport beim Carbonitrieren untersucht, im zweiten Teil die sich daraus einstellenden Randschichtzustände nach der Wärmebehandlung. Durch die Berücksichtigung verschiedener Prozesskombinationen und Porositäten können Modellansätze der Volumen- und Porendiffusion formuliert und quantitative Elementtiefenverläufe in Abhängigkeit der Prozessparameter prognostiziert und validiert werden. ◼
Acknowledgements
The IGF project (19887 N) of the research association Arbeitsgemeinschaft Wärmebehandlung und Werkstofftechnik e.V. (AWT) was supported by the German Federation of Industrial Research Associations „Otto von Guericke“ e.V. (AiF) within the framework of the program for the promotion of joint industrial research and development (IGF) by the Federal Ministry for Economic Affairs and Energy (BMWi) on the basis of a resolution of the German Bundestag. The authors gratefully acknowledge the financial support of the project. Further thanks go to Höganäs AB for providing the powder metallurgical samples.
Danksagung
Das IGF-Vorhaben (19887 N) der Forschungsvereinigung Arbeitsgemeinschaft Wärmebehandlung und Werkstofftechnik e.V. (AWT) wurde über die Arbeitsgemeinschaft industrieller Forschungsvereinigungen „Otto von Guericke” e.V. (AiF) im Rahmen des Programms zur Förderung der industriellen Gemeinschaftsforschung und -entwicklung (IGF) vom Bundesministerium für Wirtschaft und Energie (BMWi) aufgrund eines Beschlusses des Deutschen Bundestages gefördert. Die Autoren bedanken sich für die finanzielle Unterstützung des Vorhabens. Weiterer Dank gilt Höganäs AB für die Bereitstellung der pulvermetallurgischen Proben.
References
1 Grosch, J.; Küper, A.; Trautmann, F.: Einsatzhärten: Grundlagen, Verfahren, Anwendung, Eigenschaften einsatzgehärteter Gefüge und Bauteile: mit 155 Bildern und 8 Tabellen. 4., neu bearbeitete Auflage, expert verlag, 2016. – ISBN: 3816932940Search in Google Scholar
2 Dlapka, M.; Strobl, S.; Danninger, H.; Gierl, C.: Austenitkorngröße in sintergehärteten pulvermetallurgischen Stählen. Practical Metall. 1FF2 (47/2010), pp. 686–699, DOI:10.3139/147.11009910.3139/147.110099Search in Google Scholar
3 Nusskern, P.; Hoffmeister ,J.; Schulze, V.: Simulation des Einsatzhärtens gradiert poröser Bauteile: Materialmodellierung. HTM 6 (68/2013), pp. 258–266, DOI:10.3139/105.11020010.3139/105.110200Search in Google Scholar
4 Huppmann, W. J.; Dalal, K.; Wellner, P.; Elssner, G.: Metallographic Characterization of PM Materials. Powder Metall. 1 (26/1983), pp. 23–30, DOI:10.1179/ pom.1983.26.1.2310.1179/ pom.1983.26.1.23Search in Google Scholar
5 Widanka, K.: Effect of interconnected porosity on carbon diffusion depth in vacuum carburising process of iron compacts. Pow. Met. 4 (53/2010), pp. 318–322, DOI:10.1179/174329009 × 44933210.1179/174329009 × 449332Search in Google Scholar
6 Winter, K.-M.: Independently Controlled Carbon and Nitrogen Potential: A New Approach to Carbonitriding Process. J. of Mat. Engi. and Perfor. 7 (22/2013), pp. 1945–1956, DOI:10.1007/s11665-013-0556-510.1007/s11665-013-0556-5Search in Google Scholar
7 Slycke, J.; Ericsson, T.: A study of reactions occurring during the carbonitriding process part II. J. o. Heat Treating 2 (2/1981), pp. 97–112, DOI:10.1007/ bf0283322610.1007/ bf02833226Search in Google Scholar
8 Skalecki, M. G.; Klümper-Westkamp, H.; Steinbacher, M.; Zoch, H.-W.: Alloying Factors and Parameter of Alloying Elements for Carbon and Nitrogen Uptake during Carbonitriding as Basis for Simulation. HTM 2 (73/2018), pp. 80–95, DOI:10.3139/105.11035010.3139/105.110350Search in Google Scholar
9 Skalecki, M. G.; Klümper-Westkamp, H.; Steinbacher, M.; Zoch, H.-W.: Solubility of Carbon and Nitrogen and Precipitation of Carbides and Nitrides during Carbonitriding as Basis for Simulation. HTM 4 (74/2019), pp. 215–227, DOI:10.3139/ 105.11038510.3139/ 105.110385Search in Google Scholar
10 Skalecki, M. G.; Klümper-Westkamp, H.; Winter, K.-M.; Zoch, H.-W.: Controlled Carbonitriding and Simulation of Carbonitriding Process. HTM 2 (75/2020), pp. 105–120, DOI:10.3139/105.11040510.3139/105.110405Search in Google Scholar
11 Kremel, S.; Danninger, H.; Altena, H.; Yu, Y.: Low-pressure carburizing of sintered alloy steels with varying porosity. Pow. Met. Pro. 3 (4/2004), pp. 119–131, – ISSN: 1335-8987Search in Google Scholar
12 Eck, S.; Ishmurzin, A.; Wlanis, T.; Ebner, R.; Planitzer, F.; Hatzenbichler, T.: A finite element model for carburisation of surface densified PM components. Inter. J. o. Comput. Mat. Sc. and Surface Engi. 1 (5/2012), p. 16, DOI:10.1504/ ijcmsse.2012.04905110.1504/ ijcmsse.2012.049051Search in Google Scholar
13 Wells, C.; Batz, W.; Mehl, R. F.: Diffusion coefficient of carbon in austenite. JOM, 3 (2/1950), pp. 553–560, DOI:10.1007/bf0339903210.1007/bf03399032Search in Google Scholar
14 Stolar, P.; Prenosil, B.: Kinetics of Transfer of Carbon from Carburizing and Carbonitriding Atmospheres, Metall, Metall. Mat. 5 (22/1984), pp. 348–353Search in Google Scholar
15 Slycke, J. T.; Mittemeijer, E. J.; Somers, M.: 1 – Thermodynamics and kinetics of gas and gas–solid reactions. Thermochemical Surface Engineering of Steels. eds. J. T. Slycke; E. J. Mittemeijer; M. A. J. Somers Woodhead Publishing, 2015, pp. 3–111, – ISBN: 978085709592310.1533/9780857096524.1.3Search in Google Scholar
16 Gierl-Mayer, C.; Gonzalez, M. S.; Schmidt, J.; Specht, E.; Danninger, H.: Thermophysical properties of sintered steels – Effect of porosity and composition. World-PM, 2010, pp. 41–50, – ISBN: 9781899072101Search in Google Scholar
17 Nußkern, P.: Prozesssimulation der Herstellung einsatzgehärteter pulvermetallurgischer Bauteile. Dissertation. KIT. Karlsruhe, 2013Search in Google Scholar
18 Damon, J.; Dietrich, S.; Vollert, F.; Gibmeier, J.; Schulze, V.: Process dependent porosity and the influence of shot peening on porosity morphology regarding selective laser melted AlSi10Mg parts. Add. Manufac. (20/2018), pp. 77–89, DOI:10.1016/j.addma.2018.01.00110.1016/j.addma.2018.01.001Search in Google Scholar
19 Schwarz, B.; Göhring, H.; Meka, S. R.; Schacherl, R. E.; Mittemeijer, E. J.: Pore Formation Upon Nitriding Iron and Iron-Based Alloys: The Role of Alloying Elements and Grain Boundaries. Metall. and Mat. Trans. A 13 (45/2014), pp. 6173–6186, DOI:10.1007/s11661-014-2581-x10.1007/s11661-014-2581-xSearch in Google Scholar
20 Dlapka, M.; Danninger, H.; Gierl, C.; Lindqvist, B.: Defining the pores in PM components. Metal Pow. Rep. 2 (65/2010), pp. 30–33, DOI:10.1016/s0026-0657(10)70093-x10.1016/s0026-0657(10)70093-xSearch in Google Scholar
21 Damon, J.; Dietrich, S.; Schulze, V.: Implications of carbon, nitrogen and porosity on the martensite phase transformation and resulting hardness in PM-steel Astaloy 85Mo. J. o. Mat. Res. and Tech. 4 (9/2020), pp. 8245–8257, DOI:10.1016/ j.jmrt.2020.05.03510.1016/ j.jmrt.2020.05.035Search in Google Scholar
© 2021 Walter de Gruyter GmbH, Berlin/Boston, Germany
Articles in the same Issue
- Inhalt/Contents
- Influence of the Material State of Ground, Case-Hardened Steels on the Barkhausen Noise Depending on the Surface Integrity*
- Suitable Material Selection for Large Size Cylindrical Gears*
- Experimental and Numerical Investigation of the Surface Layer Conditions after Carbonitriding of Powder Metallurgical Steels. Part 1: Diffusion in Components of Graded Porosity
- Plasma Nitriding Mechanisms of Low-Density Sintered Metal Products
- Heat Transfers Coefficients of Directly and Indirectly Cooled Component Areas during Air-Water Spray Cooling
- Impressum/Imprint
- From and for Practice / Praxis-Informationen
- AWT-Info / HTM 01-2021
- HTM Praxis
Articles in the same Issue
- Inhalt/Contents
- Influence of the Material State of Ground, Case-Hardened Steels on the Barkhausen Noise Depending on the Surface Integrity*
- Suitable Material Selection for Large Size Cylindrical Gears*
- Experimental and Numerical Investigation of the Surface Layer Conditions after Carbonitriding of Powder Metallurgical Steels. Part 1: Diffusion in Components of Graded Porosity
- Plasma Nitriding Mechanisms of Low-Density Sintered Metal Products
- Heat Transfers Coefficients of Directly and Indirectly Cooled Component Areas during Air-Water Spray Cooling
- Impressum/Imprint
- From and for Practice / Praxis-Informationen
- AWT-Info / HTM 01-2021
- HTM Praxis
