INVESTIGATION OF THE STEAM OXIDATION RESISTANCE OF SANICRO 25 - A MATERIAL FOR SUPERHEATER AND REHEATERS IN HIGH EFFICIENCY A-USC FOSSIL POWER PLANTS

摘要

Sanicro 25 material is approved for use in pressure vessels and boilers according ASME code case 2752, 2753 and VdTUV blatt 555. It shows higher creep rupture strength than any other austenitic stainless steels available today. It is a material for superheater and rehaaters, enabling higher steam parameters of up to about 650°C steam (ie about max 700°C metal) without the need for expensive nickel based alloys. The aim of the present study is the investigation of the steam oxidation resistance of the Sanicro 25. The long term test was conducted in the temperature range 600 -750°C up to 20 000 hours. The morphology of the oxide scale and the microstructure of the bulk material were investigated. In addition, the effect of surface finish and pressure on the steam oxidation were also studied.