Degradation of Aluminide Layers During Cyclic Oxidation of Ferritic 430 Stainless Steel
ABSTRACT: In order
to increase the
performance of the
preferred Ferritic 430
SS for manufacturing automobile and
motor-cycle exhaust systems.
The aluminizing coating
on the surface
of bare steel was
applied by hot-dipping
method in a
molten pure aluminum.
The high temperature oxidation of the aluminized steel
was cyclically studied at 900 °C and 1000 °C in static air. The degradation of
intermetallic layers during
cyclic oxidation were
analyzed by means
of X-ray Diffraction (XRD),
Scanning Electron Microscopy
(SEM) and Energy
Dispersive Spectroscopy (EDS). The
crack perpendicular to the specimen
surface rapidly propagated
through the FeAl and Fe3Al layers due to a thermal
expansion mismatch upon cooling to room temperature. The accumulation of voids
generated crack at the interface between the aluminide layer and the steel substrate. Oxygen
is allowed to
penetrate into the
aluminide layer crack,
rapidly forming alumina oxide and
closing the crack. Some of the aluminide layers peeled off due to this rapid growth. Thus,
the protective Al2O3
layer degraded and
later, the substrate
was oxidized subsequently to form
iron-rich oxide (Fe2O3) at 1000 °C.
Author: Mohammad Badaruddin
Journal Code: jptmesingg110002
