EFFECTS OF METALLOGRAPHIC PREPARATION PROCEDURES ON CREEP DAMAGE ASSESSMENT

Specimens taken from a ruptured Cr-Mo steel steam tube and a cast austenitic reformer tube exposed at high temperature for extended time have been examined for creep damage, using mechanical polishing procedures. It is demonstrated that the presence of damage may be observed readily or missed depending on the surface preparation procedure followed. The nature of the observed damage is discussed together with the ways in which the surface preparation procedures affect its disclosure. The implications of metallographic preparation procedures on the assessment of creep damage and remaining life estimation are reviewed, and a procedure to ensure reliable identification of such damage is recommended.