Microstructure of TP304H Austenitic Boiler Tubes Operated at High Temperatures

Investigations of bend TP304H tube in an 1021 t/h boiler which operated at high temperature for 62000 h was carried out by means of metallurgic inspection,energy dispersive X-ray (EDX) and other tests.The microstructure and morphology features of TP304H austenitic stainless steel tube operated at high temperature for long time were investigated.The results showed that corrosive media,tube wall temperature and stress had great influence on microstructure of TP304H tube.Intergranular corrosion in the gas side was more severe than that in the steam side.From the steam side to the gas side along the wall direction the intergranular corrosion weakened firstly,and reached the lightest in the middle of the wall,and was intensified slightly then.