High-temperature carburization behaviour of HASTELLOY X in CH4 gas

Ni-base wrought alloy HASTELLOY X tube was exposed to Ar–CH4 at 800 and 1000 °C in order to understand the carburization kinetics of the alloy used for fuel injection nozzles of micro-gas turbine combustors. Three different internal carbides, (Cr,Mo)3C2, (Cr,Mo)7C3 and (Cr,Mo)23C6 were observed in this order from the surface, and the partial damage to the outer surface of the specimen tube appeared similar to metal-dusting. The internal carburization kinetics on both the inner and outer parts of tube followed the parabolic rate law. The carbon permeability in HASTELLOY X was obtained, and was slightly smaller than that of Ni–20%Cr.

► Three different internal carbides were formed in Hastelloy X alloy in Ar–CH4 1000 °C.
► The internal carburization kinetics followed the parabolic kinetics, and the permeability of carbon in the alloys were slightly smaller than Ni–20Cr.
► Partial damage to the outer surface was also occurred, and it appeared similar to metal-dusting.