Microstructure of Z-Phase Strengthened Martensitic Steels: Meeting the 650°C Challenge

Abstract:

We studied three series of Z-phase strengthened steels using scanning electron microscopy, transmission electron microscopy, and atom probe tomography to reveal the detailed microstructure of these steels. In particular, the phase transformation from M(C,N) to Z-phase (CrMN) was studied. Carbon content in the steels is the governing factor in this transformation. The impact toughness of some test alloys was rather low. This is attributed to the formation of a continuous W-rich film along prior austenite grain boundaries. Cu and C addition to the test alloys changed Laves phase morphology to discrete precipitates and improved toughness dramatically. BN particles were found in some steels. Formation of BN is directly linked to the B concentration in the steels.

• Periodical: Materials Science Forum (Volume 879)
• Pages: 1147-1152
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.879.1147
• Online since: November 2016
• Authors: Fang Liu*, Masoud Rashidi, John Hald, Lutz Reißig, Hans Olof Andrén
• Keywords: Atom Probe Tomography, Precipitation, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Z-Phase Strengthening

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