Tensile tests are conducted on specimens normalized at 900 °C, followed by the application of alternating current pulses at peak currents of 900 A and 1100 A. The resulting microstructural changes are analysed using metallographic techniques and a Python based image processing algorithm to quantify grain boundary thickness. A multiphysics based finite element analysis model developed in COMSOL Multiphysics facilitates the simulation of mechanical, thermal, and electromagnetic interactions during tensile loading. The results indicate that increasing electrical pulse frequency leads to a reduction in yield stress and an enhancement in ductility, peaking at approximately 0.83 Hz before declining due to fracture strain effects. While current amplitude and frequency primarily influenced failure strain, the reduction in grain boundary thickness cause by pulsed current and the associated dislocation movement significantly impacted yield and ductility properties. Statistical analysis confirms that grain boundary thicknesses in samples treated with pulsed currents were significantly lower compared to those in untreated samples. Additionally, temperature measurements indicate that these grain boundary reductions occur at strikingly low temperatures, well below the recrystallization temperature of the low carbon steel.
Abeygunawardane et al. (Wed,) studied this question.