Estimation of the residual life of L17HMF cast steel elements after long-term service

Purpose: of this paper is to present the changes of the mechanical properties and structure in material components of the power station boiler after long-term creep service made of G17CrMoV5-10 low-alloyed cast steel. Design/methodology/approach: The material of the research studies has been obtained from Polish power stations. Examined element has exceeded their assessed life of 105.000 hours. Mechanical properties and structure examinations were carried out on material after long-term service in creep conditions. The microstructure has been observed using a light and a scanning electron microscope. The investigation of the development of the precipitation processes was done by X-ray diffraction phase analysis. Findings: The microstructures and phase compositions of the residues, obtained from the elements, depend on life exhaustion extent. Practical implications: The presented method can be used for evaluation and qualification of structural changes in power station boiler and turbine components operating in creep conditions. Originality/value: The paper presents results of changes in the mechanical properties, structure and in the precipitation processes which are applied to evaluation for the condition of the elements in further industrial service.