Improvement in Tensile and Fatigue Behavior of Steels by the Application of Pulsed Electric Current

Abstract

Steels are widely utilized in many industries like automotive, manufacturing, energy, aerospace, construction, and consumer goods sectors. However, the performance of metallic engineering structures can be influenced by external factors such as fatigue loading, pre-strain, and hydrogen effects. These factors have the potential to cause damage and component failure, leading to reduced service life and compromised safety. Therefore, it is crucial to repair such damages and restore the mechanical properties of metallic components, particularly in industries where these components are subjected to diverse loading conditions and environments. newlineThis study focuses on investigating the potential of electric pulse treatment (EPT) on damage healing and improving the mechanical properties of dual-phase (DP 780) and drawing quality (DQ) steels. Initial damages in steel specimens are introduced through low cycle fatigue (LCF) test, uniaxial tensile pre-straining, and hydrogen embrittlement (HE). The damaged specimens are then treated with pulsed electric current using different electro-pulsing parameters. Electron backscatter diffraction (EBSD), X-ray diffraction (XRD), and scanning electron microscopy (SEM) are used to observe and quantify the change in microstructure before and after the application of pulsed electric current. The experimental results indicate that with suitable electro-pulsing parameters, micro-cracks generated by fatigue and voids generated by pre-straining in steel specimens can be healed to a large extent, thereby restoring the mechanical properties. The possible reasons behind damage healing could be Joule heating, thermal compressive stress, micro-welding between the cracked surfaces and collapse of micro-voids. The region reasonably far away from the crack shows no impact of electro-pulsing on the microstructure. Moreover, the electro-pulsing parameters play a crucial role in damage recovery. A small change in the pulse duration shows a high impact on the tensile properties of pre-strained specimens.