Microstructure and mechanical properties of TP347HFG austenitic stainless steel after long-term service

The paper presents the results of research on the microstructure and mechanical properties of TP347HFG steel after long-term service. The test samples for research were taken from the coil of a boiler superheater serviced for 105 000 hat a steam pressure of 12.5 MPa at the temperature of 540 degrees C. The tests have shown that the process of long-term service of the steel mostly contributed to the processes of precipitation of secondary particles: M23C6 and MX, and the matrix recovery. The changes in the microstructure of the steel had a fairly minor influence on the strength and creep properties. The extent of degradation of the steel microstructure and mechanical properties was relatively minor, which resulted from its low temperature of service.