ASSESSMENT OF MICROSTRUCTURE DEGRADATION OF CREEP EXPOSED BOILER STEELS
Under the influence of temperature and stresses, the heat resistant materials react by creeping. Boiler components subjected to creep have a limited lifetime. Creep and material structure evolution are tightly related and according to this rule a number of studies have been performed in order to relate micro structural investigation and service exposure or residual life. The determination of the structural conditions and the materials exhaustion of creep exposed power plant boiler components is increasingly carried out by field of metallography. For assessment of damage and of the risk associated with failure it is necessary to know the potential mechanisms of degradation and the rate of accumulation of damage. VGB-TW 507 represents guideline for the assessment of microstructure and damage development of creep exposed materials for pipes and boiler components.