Advertisement

Journal of Materials Science

, Volume 50, Issue 6, pp 2594–2604 | Cite as

Thermo-physical properties of heat-treatable steels in the temperature range relevant for hot-stamping applications

  • Jakob Kuepferle
  • Jens Wilzer
  • Sebastian Weber
  • Werner Theisen
Original Paper

Abstract

In many industrial processes, the resulting mechanical properties of produced steel parts are directly influenced by the thermo-physical properties, which affect the heat treatment significantly. The quality of application-oriented simulations is strongly dependent on the input quantities, which are often generated by regression analysis or simple extrapolations. The aim of this paper is to demonstrate the influence of the thermo-physical properties on such a process simulation referring to the hot stamping. Hot stamping is an established process in the automotive industry to produce ultra-high strength parts. A typical material used for this application is the low-alloyed steel 22MnB5. The thermal conductivity of this steel was investigated referring to the temperature-dependent microstructural changes during the hot-stamping process, particularly the γ to α′ transformation. In terms of the dynamic measuring method, the specific heat capacity, the thermal expansion coefficient, the density and the thermal diffusivity for the different temperature-dependent microstructures of the steel 22MnB5 were determined. The thermal conductivity for the complete temperature range of the hot-stamping process was generated, referring to measured and extrapolated data. To account for the fast γ–α′ transformation kinetics, a novel characterization and extrapolation method was applied. The heat capacity and the thermal diffusivity have a major impact on the thermal conductivity compared to the subordinated influence of the density. The metastable austenitic condition (T ≥ 900 °C) was compared to the martensitic condition (T ≤ 400 °C). The dependent thermal conductivity is significantly dependent on the crystallographic orientation of the lattice. The face-centred cubic lattice (austenite) has referring to the body-centred cubic lattice (martensite), a proportionally low thermal conductivity. During the transformation from austenite to martensite, the development is not linear but based on complex interactions. The results reveal that the temperature-dependent thermal conductivity has to be considered for reliable process simulations.

Keywords

Austenite Martensite Thermal Diffusivity Pearlite Thermal Expansion Coefficient 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

References

  1. 1.
    Takahashi M (2003) Development of High strength steels for automobiles. Nippon steel technical report, No. 88, 295–415Google Scholar
  2. 2.
    Karbasian H, Tekkaya A (2010) A review on hot stamping. J Mater Process Technol 210:2103–2118CrossRefGoogle Scholar
  3. 3.
    Neugebauer R, Altan T, Geiger M (2006) Sheet metal forming at elevated temperatures. Ann CIRP 55(2):2103–2118CrossRefGoogle Scholar
  4. 4.
    Naderi M (2008) Hot stamping of ultra-high strength steels. Dissertation, RWTH AachenGoogle Scholar
  5. 5.
    Merklein M, Lechler J (2006) Investigation of the thermo-mechanical properties of hot stamping steels. J Mater Process Technol 177:452–455CrossRefGoogle Scholar
  6. 6.
    Merklein M, Lechler J, Gödel V (2007) Mechanical properties and plastic anisotropy of 22MnB5 of the quenchable high strength steel 22MnB5 at elevated temperatures. Key Eng Mater 344:79–86CrossRefGoogle Scholar
  7. 7.
    Geiger M, Merklein M, Hoff C (2005) Basic investigation on the hot stamping steel 22MnB5. Adv Mater Res 6–8:795–804CrossRefGoogle Scholar
  8. 8.
    Nishibata T, Kojima N (2013) Effect of quenching rate on hardness and microstructure of hot-stamped steel. J Alloy Compd 577S:S.549–S554CrossRefGoogle Scholar
  9. 9.
    Naderi M, Ketabchi M, Abbasi M (2011) Analysis of microstructure and mechanical properties of different high strength carbon steels after hot stamping. J Mater Process Technol 211:1117–1125CrossRefGoogle Scholar
  10. 10.
    George R, Bardelcik A, Worswick M (2012) Hot forming of boron steels using heated and cooled tooling for tailored properties. J Mater Process Technol 212:2386–2399CrossRefGoogle Scholar
  11. 11.
    Perez-Santiago R, Billur E, Ademaj A (2013) Hot stamping a B-pillar with tailored properties: experiments and preliminary simulation results. Int. Hot Stamping Conferences, Lulea, SwedenGoogle Scholar
  12. 12.
    Akerstroem P, Oldenburg M (2006) Austenite decomposition during press hardening of a boron steel—computer simulation and test. J Mater Process Technol 174(2006):399–406CrossRefGoogle Scholar
  13. 13.
    Kittel C (2006) Einfuehrung in die Festkoerperphysik, 14th edn. Oldenbourg, MuenchenGoogle Scholar
  14. 14.
    Xing Z, Bao J, Yang Y (2009) Numerical simulation of hot stamping of quenchable boron steel. Mater Sci Eng A 499:28–31CrossRefGoogle Scholar
  15. 15.
    Yanagida A, Kurihara T, Azushima A (2010) Development of tribo-simulator for hot stamping. Int. Hot Stamping Conferences, Lulea, SwedenGoogle Scholar
  16. 16.
    Tritt T (2010) Thermal conductivity. Springer, New YorkGoogle Scholar
  17. 17.
    Windmann M, Röttger A, Theisen W (2013) Phase formation at the interface between a boron alloyed steel substrate and an Al-rich coating. Surf Coat Technol 226:130–139CrossRefGoogle Scholar
  18. 18.
    Patterson J, Morris E (1994) Measurement of absolute water density, 1°C to 40°C. Metrologia 31(4):277–288CrossRefGoogle Scholar
  19. 19.
    Parker W, Jenkins R, Butler C (1961) Flash method of determining thermal diffusivity, heat capacity, and thermal conductivity. J Appl Phys 32(9):1679–1684CrossRefGoogle Scholar
  20. 20.
    Kaschnitz E, Ebner R (2007) Thermal diffusivity of the aluminum alloy Al–17Si–4Cu (A390) in the solid and liquid states. Int J Thermophys 28(2):711–722CrossRefGoogle Scholar
  21. 21.
    Kaschnitz E, Kueblboeck M (2008) Thermal diffusivity of the aluminum alloy Al–5Mg–2Si–Mn (magsimal-59) in the solid and liquid states. High Temp High Press 37:221–230Google Scholar
  22. 22.
    Reed R, Clark A (1983) Materials at low temperatures. American Society for Metals, Metals ParkGoogle Scholar
  23. 23.
    Tritt T, Weston D (2010) Measurement techniques and considerations for determining thermal conductivity of bulk materials. In: Tritt T (ed) Thermal conductivity. Springer, New York, pp 187–203Google Scholar
  24. 24.
    Richter F (1984) Die spezifische Waermekapazitaet von metallischen Werkstoffen.-II.Teil: Austenitische Staehle. Archiv fuer das Eisenhuettenwesen 55, Nr.4Google Scholar
  25. 25.
    Cezairliyan A, Anderson A, Bonnel D (1988) Specific heat of solids, I-2 edn. Hemisphere, New YorkGoogle Scholar
  26. 26.
    Richter F (1973) Die wichtigsten physikalischen Eigenschaften von 52 Eisenwerkstoffen: Mitteilung aus dem Forschungsinstitut der Mannesmann AG, vol. Heft 8. Stahleisen, DuesseldorfGoogle Scholar
  27. 27.
    Richter F (1983) Physikalische Eigenschaften von Staehlen und ihre Temperaturabhaengigkeit: Polynome und graphische Darstellungen, vol. Heft 10, Stahleisen, DuesseldorfGoogle Scholar
  28. 28.
    Pepperhoff W, Acet M (2001) Constitution and magnetism of iron and its alloys. Springer, BerlinCrossRefGoogle Scholar
  29. 29.
    Norm ASTM E1461-01 (2001) Standard test method for thermal diffusivity by the flash method. American Society for Testing and MaterialsGoogle Scholar
  30. 30.
    Carslaw HS, Jaeger JC (1986) Conduction of heat in solids, 2nd edn. Clarendon Press and Oxford University Press, Oxford c1959Google Scholar
  31. 31.
    Burgel R, Maier H, Niendorf T (2011) Handbuch Hochtemperatur-Werkstofftechnik: Grundlagen, Werkstoffbeanspruchungen, Hochtemperaturlegierungen und –beschichtungen, 4th edn. Vieweg+Teubner, WiesbadenCrossRefGoogle Scholar
  32. 32.
    Carslaw H, Jaeger J (1980) Conduction of heat in solids. Clarendon, OxfordGoogle Scholar
  33. 33.
    Stankus S, Savchenko I, Baginskii A (2008) Thermal conductivity and thermal diffusivity coefficients of 12Kh18N10T stainless steel in a wide temperature range. High Temp 46(5):731–733CrossRefGoogle Scholar
  34. 34.
    Uher C (2010) Thermal conductivity of metals. In: Tritt T (ed) Thermal conductivity. Springer, New York, pp 22–88Google Scholar
  35. 35.
    Yang J (2010) Theory of thermal conductivity. In: Tritt T (ed) thermal conductivity. Springer, New York, pp 1–20Google Scholar
  36. 36.
    Williams R, Graves R, Weaver F (1987) Effect of point defects on the phonon thermal conductivity of bcc iron. J Appl Phys 62(7):2778–2783CrossRefGoogle Scholar
  37. 37.
    Korzhavyi PA, Ruban AV, Odqvist J (2009) Electronic structure and effective chemical and magnetic exchange interactions in bcc Fe–Cr alloys. Phys Rev B 79(5):054202CrossRefGoogle Scholar
  38. 38.
    Bungardt K, Spyra W (1965) Waermeleitfaehigkeit unlegierter und legierter Staehle und Legierungen bei Temperaturen zwischen 20 und 700 °C. Archiv fuer das Eisenhuettenwesen 36(4):257–267Google Scholar
  39. 39.
    Valls I, Casas R, Rodriguez N, Paar U (2010) Benefits from using high thermal conductivity tool steels in the hot forming of steels. La Metallurgia Italiana 11–12:23–28Google Scholar

Copyright information

© Springer Science+Business Media New York 2015

Authors and Affiliations

  • Jakob Kuepferle
    • 1
  • Jens Wilzer
    • 1
  • Sebastian Weber
    • 2
  • Werner Theisen
    • 1
  1. 1.Lehrstuhl Werkstofftechnik, Institut fuer WerkstoffeRuhr-Universitaet BochumBochumGermany
  2. 2.Fachbereich D, Abteilung Maschinenbau, Lehrstuhl fuer neue Fertigungstechnologien und WerkstoffeBergische Universitaet WuppertalSolingenGermany

Personalised recommendations