Analysis on Cracking Reason of Boiler Platen Reheater Tubes in Thermal Power Plant

The cracking reason and failure mechanism of the platen reheater tubes in thermal power plant were investigated by macroscopic examination, chemical composition analysis, metallographic examination, scanning electron microscopy and field investigation. The results showed that the transverse cracks on platen reheater tubes were intergranular cracks caused by thermal fatigue and creep interaction. There were fatigue striations and creep cavities on the fracture surface. Thermal fatigue and creep in platen reheater tubes were due to large expansion because of material large thermal expansion coefficient, thermal stress by blocked expansion and long-term overheating.