Precipitation of Secondary Phases in a Supermartensitic 13Cr6Ni2.5MoTi Steel during Heat Treatment

Abstract:

The balance between strength and toughness of supermartensitic steels can be controlled by heat treatment parameters. Quality heat treatment usually consists of quenching and single or double tempering above the A_c1 temperature. Such a treatment results in stabilization of reverted austenite in the tempered martensite. Tempering can also be accompanied by intensive precipitation processes, especially in high alloyed grades. A detailed TEM characterisation of precipitation processes in a 13Cr6Ni2.5MoTi supermartensitic steel proved that single tempering at temperatures of 600°C and 690°C was accompanied by precipitation of three minor phases: MX (TiX), M₂₃C₆ and Laves phase (Fe₂Mo type). Precipitation processes were more intensive at 690°C. Volume fractions of MX and M₂₃C₆ phases were low. Laves phase precipitation was intensive and particles of this minor phase grew fast. However, thermodynamic calculations using the Thermocalc software suggest that Laves phase is not an equilibrium phase in the steel under consideration.

• Periodical: Materials Science Forum (Volume 891)
• Pages: 161-166
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.891.161
• Online since: March 2017
• Authors: Gabriela Rožnovská*, Vlastimil Vodárek, Zdeněk Kuboň
• Keywords: Heat Treatment, Precipitation, Reverted Austenite, Supermartensitic Steels, ThermoCalc

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