Achieving Synergistic Enhancement of Strength Ductility in 2205 Duplex Steel via Short-Time Pulse Current

Abstract

The direct application of pulsed electric current (PEC) treatment to materials can induce microstructural modifications and thus improve mechanical properties compared to conventional heat treatments. Pulsed current treatments are characterized by simplicity, speed, and low energy consumption. This study explores the effects of PEC treatment at varying current densities on the mechanical properties and microstructure of 2205 duplex stainless steel. A current density of 19.5 A/mm² increases tensile strength by 36 MPa and elongation by 5.7% compared to the original rolled sample, resulting in superior mechanical properties. Comparative analysis with isothermal annealing, conducted at equivalent temperature and duration, reveals that the PEC treatment modification process is not solely attributable to thermal effects but rather represents a synergistic interaction between non-thermal and thermal effects. Electron backscatter diffraction (EBSD) analysis reveals that PEC treatment can refine grain size and adjust the austenite-ferrite ratio. Field emission transmission electron microscopy (TEM) shows that PEC treatment facilitates dislocation movement, forming dislocation lines and walls, and promotes recrystallization nucleation. Energy dispersive X-ray spectroscopy (EDS) indicates enhanced diffusion of alloying elements, reduced austenite stability, and phase transformation under PEC treatment. This study underscores the potential of PEC treatment in advancing the mechanical performance of duplex stainless steels. The simplicity, rapidity, and low energy consumption inherent to PEC processing make it a compelling choice for manipulating these materials.