Experimental study demonstrates enhanced joint strength and nugget size in welded dissimilar steel, indicating benefits of magnetic-field assistance.
Key Points
To evaluate how magnet working distance influences external magnetic-field distribution, weld-nugget geometry, microstructure, and mechanical properties in dissimilar steel spot welds.
Conducted 3D magnetostatic simulations across magnet working distances of 34, 28, and 22 mm.
Characterized joint performance via tensile–shear testing, optical microscopy of dendritic morphology, and microhardness testing.
Simulated magnetic flux density at the geometric weld center increased from 23.88 mT at H = 34 mm to 41.63 mT at H = 28 mm and 82.39 mT at H = 22 mm.
Mean nugget diameter increased from 5.14 ± 0.14 mm in conventional RSW to 5.67 ± 0.14 mm at H = 22 mm, while peak tensile–shear load rose 15.1% from 5738.6 ± 177.5 N to 6604.1 ± 211.1 N.
Equivalent fusion area enlarged by approximately 21.7%, accompanied by a finer and less directionally oriented dendritic microstructure.