Effect of pulse current on mechanical properties and dendritic morphology of modified medium manganese steel welds metal

Modified medium manganese steel (MMMS) samples were joined using gas metal arc welding (GMAW) and pulse-GMAW (P-GMAW) techniques. The joints were examined using optical microscope, scanning electron microscope, hardness tests, tensile tests and side bend tests. The use of P-GMAW was found to be superior to the GMAW process, resulting in a noteworthy enhancement of the plastic deformation capacity of the weld joint while maintaining comparable tensile properties. Microstructural study and measurement of primary and secondary dendrite arm spacing were also performed to better understand the important aspects of weld metal solidification, i.e., pulse current. The treatment with pulse current restrained the dendrite growth in the welds, resulting in finer dendritic grains, which improved the ductility of the weld joint. The refinement of the microstructure can be attributed to the application of the pulse current, which intensified the effective vibration of the molten pool, facilitated the diffusion of the alloy and reduced the microsegregation.