摘要
A metallurgical forensic investigation was conducted to determine the cause of a failed superheater tube. Analysis techniques by Visual Examination, Energy Dispersive X-ray Analysis, Mechanical Testing and Metallographic Investigation were conducted, together with a comparative study from an inlet elbow section that did not fail. The superheater tube suffered premature failure after being in service for about two years. It was concluded that the failed tube underwent overheating, corrosion-erosion, embrittlement, and eventual failure under its internal pressure by stress rupture. The analysis revealed intergranular cracks, window fracture features and spheroidization of pearlite with grain growth. A possible contribution to embrittlement was from copper. Follow-ups and recommendations were provided, as well as covering materials, inspection, and operational considerations.
A metallurgical forensic investigation was conducted to determine the cause of a failed superheater tube. Analysis techniques by Visual Examination, Energy Dispersive X-ray Analysis, Mechanical Testing and Metallographic Investigation were conducted, together with a comparative study from an inlet elbow section that did not fail. The superheater tube suffered premature failure after being in service for about two years. It was concluded that the failed tube underwent overheating, corrosion-erosion, embrittlement, and eventual failure under its internal pressure by stress rupture. The analysis revealed intergranular cracks, window fracture features and spheroidization of pearlite with grain growth. A possible contribution to embrittlement was from copper. Follow-ups and recommendations were provided, as well as covering materials, inspection, and operational considerations.
作者
Kok Toong Leong
Kok Toong Leong(Engineering Department, QSM Associates, Singapore)
