Title

USE OF THE ELECTROCHEMICAL MICROCELL TECHNIQUE FOR STUDYING PITTING CORROSION AT WELDED JOINTS OF LEAN DUPLEX STAINLESS STEEL UNS S32304

Authorship

Dalila Chaves Sicupira; Ronaldo Cardoso Júnior; Alexandre Queiroz Bracarense; Gerald Frankel; Vanessa de Freitas Cunha Lins

Dalila Chaves Sicupira

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Ronaldo Cardoso Júnior

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Alexandre Queiroz Bracarense

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Gerald Frankel

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Vanessa de Freitas Cunha Lins

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DOI

10.5151/12abinox-26638

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Abstract

A pitting corrosion study of welded joints of lean duplex stainless steel (LDSS) UNS S32304 has been performed. LDSS S32304 thick plates were welded by different processes commonly employed in equipment and piping construction: SMAW (Shielded metal arc welding), GMAW (Gas metal arc welding) and FCAW (Flux cored arc welding). The electrochemical behavior of different weldment zones (fusion zone (FZ), base metal (BM) and heat affected zone (HAZ)) was characterized both independently using an electrochemical microcell and together through whole sample analysis. The electrochemical method applied was performed in acidified glycerin, a process fluid of the biodiesel industry. The results were correlated to the microstructural features of the materials. Based on the results, is possible to conclude that the breakdown potential (Eb) of the fusion zone (FZ) was higher than the Eb obtained for the heat affected zone (HAZ). In general, top samples show higher breakdown potential than root samples and also the samples welded using filler metal 2209 has a better anodic behavior than the filler metal 2307. According to the results, GMAW welding process with 2209 as filler metal was revealed as the optimum chosen for application of 2304 duplex stainless steels in this case.

Keywords

Pitting corrosion; LDSS; Welding process; Microcell