Abstract
Welding parameters can greatly affect the final product. In this study, there was a variation given on the pulse energy, i.e., heat input parameters. The microstructure was analyzed and presented in relation to the efficiency of corrosion. The microstructural study showed the changes of the fusion zone (FZ) and the heat-affected zone (HAZ) with an increase in pulse energy. The development of a prominent austenite process on the weld material had a prolonged effect on its corrosion resistance property. Electrochemical impedance spectroscopy (EIS) and potentiodynamic measurements were used to test the electrochemical activity of laser-weld 2205 duplex stainless steel in an aqueous 3.5% NaCl solution. Finally, the findings of the EIS analysis were supported by Raman spectroscopy. Based on the obtained results, the 2205 duplex stainless steel (DSS) weld obtained at a higher pulse energy showed higher corrosion resistance than the welded sample obtained at a low pulse energy. The impedance spectroscopy confirmed a smooth surface property with an increase in the pulse energy and the presence of an oxide layer, a finding also confirmed by the Raman spectroscopy measurements.
Highlights
There are several advantages of using duplex stainless steel over the austenitic grades.Duplex grades are cost-effective and lightweight compared to their austenitic counterparts, though the latter possess better corrosion resistance and approximately double the yield strength in some cases
It can be deduced that the passive films in 2205 duplex stainless steel with higher pulse energy will have significantly higher corrosion resistance as compared to those with lower pulse energy
The results of the Raman spectra suggest that the increase in the concentration of hematite in 2205 duplex stainless steel may lead to a decrease in the passive film point defects
Summary
There are several advantages of using duplex stainless steel over the austenitic grades. The DSS does not have sufficient time to form an austenitic phase during laser welding in the case of low heat input and rapid cooling. The main difference for duplex grades is the higher heat input relative to laser welding, resulting in decreased cooling rates and improved austenite forming [16,17]. The ferrite–austenite phase ratio of DSSs must be preserved at close to 50:50 in order to obtain the required mechanical properties and corrosion resistance properties This phase ratio equilibrium can be hampered by the slow/fast-cooling thermal cycles in the welding process. A significant amount of ferrite phase and chromium nitride (Cr2N) particles are generated at a low heat input or during the rapid cooling process. The effect of pulse energy on the microstructural and corrosion behavior properties of the welded DSS has been investigated
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