Abstract
The influence of heat treatments between 400 and 750°C on the intergranular corrosion, general corrosion and pitting behaviour of duplex 329 stainless steel was studied.
It was found that ageing for 1h at 500–650°C slightly sensitised the duplex alloy to intergranular corrosion. Only the electrochemical potentiokinetic reactivation method (EPR) was capable of distinguishing between mildly sensitised and unsensitised specimens. Notwithstanding this, the overall corrosion resistance was markedly decreased by heat treatments in the range of temperature, 500–650°C. An abrupt decrease in pitting potential values and an increase in pit dimension and density were observed, respectively, in polarisation tests and galvanostatic pitting experiments.
The average corrosion rates calculated from weight loss on as-received and aged samples after immersion in sulphuric acid solutions and ferric chloride solutions were in agreement with previous findings.
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