Effect of Service Exposure on Material Properties of Austenitic Boiler Steels

A long-term field exposure test of austenitic stainless steels developed through the early 1980s was conducted at Eddystone Power Station Unit No.1, which has highest steam parameters worldwide to date. The experimental lengths include TP347 chromized, Tempaloy A-1, TP347HFG and 17-14CuMo/310S coextruded, and were service-exposed in the final superheater operated at steam conditions of 1170°F (632°C) and 4550 psig (31MPa) for about ten years. The test lengths were removed from the final superheater at operating duration points of about 20,000 and 50,000 hours. In this paper the post-service creep rupture properties and changes in mechanical properties are presented and discussed through comparative study with unused materials. Steam oxidation scale growth behavior of the test steels during high-temperature superheater service is also reported.