Graphite in the low-alloyed 15Mo3 steel after service

Abstract

The process of 0,5Mo steel graphitization belongs to untypical examples of steel degradation during long-term service at elevated temperature. The paper presents the results of examination of the components of a fluidized bed boiler in which the process took place. Examinations with a light and scanning microscope, a microanalysis of the chemical composition and phase analysis provide explicit documentation for the case discussed. The real equivalent sevice temperature determined indicates the direct cause for the occurrence of such material degradation.