N. Hussain et al., OXIDATION OF HIGH-TEMPERATURE ALLOYS (SUPERALLOYS) AT ELEVATED-TEMPERATURES IN AIR .1., Oxidation of metals, 41(3-4), 1994, pp. 251-269
Four commercial alloys-Hastelloy C-4, alloy 1.4306S (SS 304L), Incoloy
800H, and Incoloy 825-were studied for their oxidation behavior at el
evated temperatures. Specimens were exposed to air from 600 to 1200-de
grees-C for 1 to 400 hr. Reaction kinetics of oxidation were determine
d, and the morphology of the surface-oxide scales was investigated Has
telloy C-4 showed better resistance to oxidation for exposure temperat
ures up to 1000-degrees-C in comparison with the other three alloys. I
n this temperature range, it follows a cubic rate law of oxidation due
to formation of uniform, protective, and adherent oxide scales. The l
atter three alloys obeyed the parabolic rate law at 1000-degrees-C and
1200-degrees-C, but for lower temperatures a mixed behavior was shown
. The oxide layer developed on the alloy 1.4306S was always in the for
m of stratified nodules/warts. For longer exposures the nodules joined
each other to form continuous but discrete layers. Incoloy 800H and I
ncoloy 825 behaved in an almost identical manner, their reaction kinet
ics being governed by the parabolic rate law throughout the temperatur
e range. Oxide spalling was observed at all temperatures. In contrast
to Incoloy 800H the Incoloy 825 was totally oxidized for longer exposu
res at 1200-degrees-C.