Effect of cyclic heat treatment process on the pitting corrosion resistance of EN-1.4405 martensitic, EN-1.4404 austenitic, and EN-1.4539 austenitic stainless steels in chloride-sulfate solution.
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John Wiley & Sons
Abstract
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The effect of high temperature variation on the corrosion resistance of
EN-1.4405, EN-1.4404, and EN-1.4539 stainless steels in 2 M H2SO4/3.5% NaCl
solution was studied. Untreated EN 1.4405 exhibited the highest corrosion
rate at 4.775 mm/year compared to untreated EN 1.4539 with the lowest corrosion
rate (1.043 mm/year). Repetitive heat treatment significantly decreased
the corrosion rate of the steels by 54.61%, 27.83%, and 50.28% to 2.167, 1.396,
and 0.519 mm/year. EN-1.4539 steel exhibited the shortest metastable pitting
activity among the untreated steels due to higher resistance to transient pit
formation while heat treated EN-1.4404 and EN-1.4539 steels exhibited double
metastable pitting activity. Heat treated EN-1.4405 was unable to passivate
after anodic polarization signifying weak corrosion resistance. Pitting current of
heat-treated steels was generally higher than the untreated counterparts. Heat
treatment extended the passivation range value of EN-1.4405 and EN-1.4539
steels compared to those of the untreated steels. The corrosion potential of
heat-treated steels significantly shifted to electronegative values. The optical
image of untreated and heat treated EN-1.4404 and EN-1.4539 steels were
generally similar while the images for EN-1.4405 significantly contrast each
other.
Keywords
TJ Mechanical engineering and machinery, TP Chemical technology