Experimental evaluation on weld zone of thin–laminated stacked sheets post-GTA weld of CRNO electrical steel

Electric motor industries widely use cold-rolled non-oriented (CRNO) electrical steel sheets (ESSs) as the magnetic core. The sheets are of low carbon–silicon, thin (0.5 mm), and laminated and joined as a stack with gas tungsten arc (GTA) welding. A weld zone is affected by the welding heat and dependent on welding current (30–110 A). The fusion zone (FZ) and heat-affected zone (HAZ) of the weld zone are analyzed for variation in the base metal (BM) and microstructural properties using a scanning electron microscope (SEM) and optical microscope (OM). The effects of weld depth, weld width, stress–strain relationship, filler material, and grain size are investigated with a weld current change. Tensile and micro-hardness testing in FZ and HAZ revealed a change of failure in zones, maximum fracture load, and micro-hardness. The effect of grain size and completely ferritic phases (α-phase and γ-phase) in the weld zone is also studied. All the properties variations are compared and correlated to the input welding heat on the thin–laminated, non-grain-oriented stack on ESS.