Microstructural analysis of elementary deformation and damage mechanisms in a tempered martensitic steel (FV 535) exposed to severe operating conditions

• Applicant: Professorin Dr. Victoria Yardley
• Subject Area: Mechanical Properties of Metallic Materials and their Microstructural Origins ; Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: from 2012 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 221580890

The heat-resistant tempered martensite chromium steels (with 9 to 12 wt.% Cr) currently used in fossil-fired power plant are now also considered for use as casing materials for aero-engine turbines. In this new application, higher stresses and temperatures and a higher frequency of stop/start cycles are expected than in power plant components. In addition, sensitivity to crack nucleation and propagation is more critical. Therefore, before using these steels under more severe conditions, a comprehensive understanding of the effect of microstructure, temperature and loading conditions on the creep and fatigue fracture is necessary. It is important to clarify (a) the effect of microstructure on creep and high-temperature fatigue and (b) the evolution of microstructure during static and cyclic deformation and crack growth. To achieve these objectives, mechanical testing (uniaxial creep, fatigue, creep crack growth and fatigue crack growth) and detailed microstructural characterisation using advanced scanning and transmission electron microscopy will be carried out. The results will help to understand important microstructural aspects in this new range of loading conditions. They will provide a basis for deriving deformation/damage mechanisms and serve as a basis for advanced micromechanical modelling.

• DFG Programme: Research Grants