Abstract
An attempt was made to study the corrosion behavior of austenitic stainless-steel SS 316L/Monel 400 alloy dissimilar metal welded joints using gas tungsten arc welding. This combination of welded joints is used in re-heaters and heat exchangers in gas processing and oil refining industries. The welded specimens were subjected to post-weld treatments, such as annealing and deep cryogenic treatment. The welded specimens were sectioned into five different parts: SS 316L base, SS 316L HAZ, weld, Monel HAZ, and Monel base. The polarization method and electrochemical impedance analysis were used to analyze the corrosion resistance in a NaCl solution. A polarization graph, Nyquist plot, and Bode plot were constructed for all regions, separately, for the heat-treated and cryo-treated specimens, to analyze the variation in corrosion resistance in different regions, and then the results were compared. To validate the results of electrochemical impedance analysis, scanning electron microscope (SEM) and energy dispersive spectroscope (EDS) analyses were also performed. The results indicated that the cryo-treated specimens have better corrosion resistance when compared to the annealed ones. Weld region on both specimens exhibited better corrosion resistance when compared to other zones.
Highlights
The joining of materials is an important manufacturing process used to combine metallic, as well as nonmetallic, parts for various applications
Multiple industries are actively considering numerous alternate welding techniques that would enhance the commercialization of high-performance of lightweight materials [1]
Dissimilar metal joints are employed widely in energy-demanding sectors involving oil and petroleum, marine, nuclear, thermal, and geothermal fields, where they are prone to hot corrosion and high-temperature wear
Summary
The joining of materials is an important manufacturing process used to combine metallic, as well as nonmetallic, parts for various applications. Multiple industries are actively considering numerous alternate welding techniques that would enhance the commercialization of high-performance of lightweight materials [1]. Narayanan et al (2014) have mentioned that the dissimilar metal joining is one of the most essential needs of several industries these days [2]. The dissimilar integration of austenitic stainless steels and nickel alloys has applications in oil and gas industries, as well as in chemical industries, which have low to moderate temperatures and corrosive environments. Mohandas et al (2005) has mentioned that an integration of moderate resistance of oxidation and creep strength finds applications in fossil fuel power plants, such as tubing for generators and other tools [3].
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