Electrochemical study of passive films formed on welded lean duplex stainless steel

Duplex stainless steel (DSS) has been considered as an excellent material of construction for applications where high corrosion resistance and high mechanical strength are required. The use of this material can minimize costs related to corrosion in different industries, for example, in the biodiesel industry. The objective of this study is to evaluate the electrochemical and electronic properties of passive films of thick welded joints of UNS S32304 lean duplex stainless steel (LDSS) fabricated by different welding processes, in acidified glycerin, a byproduct of the biodiesel industry. The electrochemical and electronic behavior of the passive films formed on UNS S32304 LDSS was evaluated using electrochemical impedance spectroscopy and Mott-Schottky measurements. The capacitance study shows that the passive films formed on welded DSS behave as n- and p-type semiconductors above and below the flat band potential, respectively. Furthermore, the samples welded by the gas metal arc welding process exhibited better corrosion resistance than other welding process using the same filler metal.