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Different Cooling Rates and Their Effect on Morphology and Transformation Kinetics of Martensite

  • Annika Eggbauer (Vieweg)
  • Gerald Ressel
  • Marina Gruber
  • Petri Prevedel
  • Stefan Marsoner
  • Andreas Stark
  • Reinhold Ebner
Conference paper
Part of the The Minerals, Metals & Materials Series book series (MMMS)

Abstract

The characteristics of martensitic transformation is strongly dependent on the cooling rate applied to the material. For a quenched and tempered steel, the martensitic transformation occurs below 500 °C, but in industry, cooling rates are normally characterized for cooling in the temperature regime between 800 and 500 °C. The effects of different cooling rates in the lower temperature regime were thus, not intensively investigated in the past. To this end, a 50CrMo4 steel is quenched in a dilatometer applying varying cooling rates below 500 °C. The martensite microstructure is analyzed by APT, TEM and EBSD in regard to carbon distribution, lath width and block sizes. Additionally, hardness measurements are carried out and martensite start temperatures as well as the retained austenite phase fractions are evaluated. It can be shown, that lowering the cooling rate leads to increased carbon segregation within the martensitic matrix. The main effect is a decrease in martensite hardness. Also the block size increases with lower cooling rate.

Keywords

Cooling parameter Cooling rate Martensite Auto tempering Quenched and tempered steel 

Notes

Acknowledgements

Financial support by the Austrian Federal Government (in particular from Bundesministerium für Verkehr, Innovation und Technologie and Bundesministerium für Wissenschaft, Forschung und Wirtschaft) represented by Österreichische Forschungsförderungsgesellschaft mbH and the Styrian and the Tyrolean Provincial Government, represented by Steirische Wirtschaftsförderungsgesellschaft mbH and Standortagentur Tirol, within the framework of the COMET Funding Programme is gratefully acknowledged. The TEM investigations were carried out using facilities at the University Service Centre for Transmission Electron Microscopy, Vienna University of Technology, Austria. The authors want to thank Jozef Keckes for the help with the synchrotron measurements and Francisca Martin Mendez for the help with the 3D APT measurements.

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Copyright information

© The Minerals, Metals & Materials Society 2018

Authors and Affiliations

  • Annika Eggbauer (Vieweg)
    • 1
  • Gerald Ressel
    • 1
  • Marina Gruber
    • 1
  • Petri Prevedel
    • 1
  • Stefan Marsoner
    • 1
  • Andreas Stark
    • 2
  • Reinhold Ebner
    • 1
  1. 1.Materials Center, Leoben Forschung GmbHLeobenAustria
  2. 2.Helmholtz Zentrum GeesthachtGeesthachtGermany

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