Design of martensitic/ferritic heat-resistant steels for application at 650 °C with supporting thermodynamic modelling

Abstract In view of developing novel heat-resisting steels for applications in conventional power plants with service temperatures of 650 °C, a series of martensitic/ferritic model steels with 12 wt.%Cr were studied to achieve an increased creep resistance through additional alloying with various elements for controlled precipitation of M 23 C 6 carbides, MX carbonitrides and intermetallic Laves phase. The alloy design relied on thermodynamic simulation calculations using Thermo-Calc and DICTRA. The mechanical testing concentrated on creep at 650 °C for up to 8000 h. The alloy optimization resulted in creep rupture strengths above those of the martensitic/ferritic P92 steel. The work was part of a cooperative project within the German MARCKO program.

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