Improving the Microstructure and Mechanical Properties of Laser-Welded Al–Si-Coated 22MnB5/Galvanized Steel Joints Added by Nickel

To weaken the harm of Al–Si coating and increase strength welded joints, variable thicknesses Ni foil (Ni, an austenitic formation element) were added to lap laser welding Al–Si-coated 22MnB5 hot stamping steel/galvanized steel joints. The joints’ weld appearance, microstructure, mechanical properties explored. altered from X shape a Y with increased thickness foil. During welding, was melted diluted into pool, forming δ-ferrite (a rich-Al phase low toughness strength) in fusion zone (FZ) boundary (FB). This deteriorated After adding Ni, amount size decreased. With significant foil, disappeared. However, new (fresh martensite (FM), which formed at temperature contained rich Ni) probably formed, except PM (previous (PM), high little or no Ni). heat-affected (HAZ) on side comprised coarse zone, refined + ferrite tempered FZ basic material. HAZ galvanized mainly pearlite. joint greater than that without Ni. maximum can be up 679 MPa because disappearance δ-ferrite. Meanwhile, increased. fracture mode three mixed fractures (cleavage, quasi-cleavage, dimple) one (dimple).