Abstract:
This research has been concerned with the oxidation
and corrosion of iron and mild steels, with particular
reference to the importance of the mechanical properties
of the surface oxides formed. A vibration technique has
been used as the basic means of investigation,
complemented by hot stage microscopy, thermobalance,
microscopy, etc., where applicable. It has been found
that the oxides formed on iron and steel become partially detached at the scale/metal interface continually during growth. This form of damage has been
,· found to have a profound effect on the dynamic modulus
of the oxides, and on its behaviour under thermal shock
or corrosive conditions. A particular EN2 steel has been
found to be largely resistant to sodium chloride and
sodium sulphate corrosion when preoxidised. This
enhanced corrosion resistance has been attributed to the
presence of a thin adherent oxide layer on the metal
surface, whose adherence is due to the concentration of
nickel in that region during oxidation.
The vibration apparatus and specimens have been
modified to enable tensile loading during oxidation such
that the strains that a surface oxide is able to
withstand before cracking may be measured. It has been
found that the strains to fracture increases with
increasing temperature. The application of the vibration
technique in this role as a crack detection system has been shown to be very satisfactory.