Abstract
Recent work by our group has shown that a relatively short-term (200h) hot corrosion exposure using a two-zone furnace rig is quite useful in ranking hot corrosion performance of the high-temperature alloys. However, certain alloys can be susceptible to catastrophic hot corrosion after long-term exposure; moreover, long-term hot corrosion exposure may assist in discerning performance of the alloys better than a short-term test. This paper is focused on the Type I hot corrosion resistance of high-temperature alloys exposed for 1050h/1075h at 900°C. Alloy performances were ranked by assessing weight-change behavior and metal recession measurements, which includes metal loss, average internal penetration, and maximum internal penetration. Ni-base N06230 and N06617 alloys, and Co-base Co-base nitride dispersion strengthened (NDS) alloy, R30006 and R30188 along with Fe-base N08120, exhibited good hot corrosion resistance. A number of high-temperature alloys were prone to catastrophic hot corrosion, among these are R30605, N06625, R50556, N06002, N07214, N06635. The types of corrosion products formed after 1050h/1075h exposure were studied using SEM equipped with EDS. The extent of hot corrosion attack in the alloys was compared with 200h: two-zone hot corrosion data and 1000h: burner-rig hot corrosion data for selected alloys. The long-term hot corrosion testing simulated via two-zone furnace rig was quite reliable and alloy rankings were comparable to those from a burner-rig hot corrosion test.
