CORROSION AND FATIGUE BEHAVIOUR OF WELDED AUSTENITIC STAINLESS STEEL IN DIFFERENT ENVIRONMENTS.
CORROSION AND FATIGUE BEHAVIOUR OF WELDED AUSTENITIC STAINLESS STEEL IN DIFFERENT ENVIRONMENTS.
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Date
2014-03
Authors
ALUKO, OLUWOLE
STEPHEN
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Abstract
This research work was carried out to study the effects of seawater, 0.5M
hydrochloric acid and wet steam corrosive media on the fatigue strength and
microstructure of welded austenitic stainless steel. The immersion time in
the corrosive media was 30 days to simulate the effect on stainless steel
structures/equipment in offshore and food processing applications.
Annealing heat treatment was carried out on the samples. The weight loss
method was used for the corrosion tests. From the results of the corrosion
test, seawater sample has highest weight loss of 4.0mg for the heat treated
samples and 4.5mg for the unheat-treated samples. For the different media
used, seawater sample has the highest corrosion rate of 0.64x10-6 mm/yr for
the heat treated samples and 0.72x10-6 mm/yr for the unheat-treated samples.
The findings from the fatigue tests show that seawater corroded specimen
have lower fatigue stress of 0.5x10-5 N/mm2
for the heat treated sample and
0.1x10-5 N/mm2
for the unheat-treated sample compared to the
corresponding hydrochloric acid and steam samples. The post welding heat
treatment was found to increase the mechanical properties of the austenitic
stainless steel especially tensile strength but it reduces the transformation
and thermal stresses of the samples. These findings were further
corroborated by the microstructural examination of the stainless steel
specimen.
Description
A THESIS SUBMITTED TO THE SCHOOL OF POSTGRADUATE STUDIES,
AHMADU BELLO UNIVERSITY, ZARIA
Keywords
CORROSION AND FATIGUE,, BEHAVIOUR,, WELDED AUSTENITIC,, STAINLESS STEEL,, DIFFERENT,, ENVIRONMENTS.