Influence of a Ni-foil interlayer on Fe/Al dissimilar joint by laser penetration welding

Laser penetration welding of a steel-on-aluminium overlap configuration with Ni-foil interlayer was investigated. The steel-on-aluminium overlap configuration prevented the formation of intermetallic compounds inside the fusion zone. A new intermetallic compound Al0.9Ni1.1 was discovered to have formed between the fusion zone and Al alloy, in addition to FeAl3, compared to a joint with no Ni-foil interlayer. The Ni-foil interlayer improved the metallurgical reaction at the interfacial zone, which decreased the microhardness of interfacial intermetallic compounds and enhanced the toughness of the joint. The tensile property of the joint with Ni-foil interlayer is higher than that of the joint without Ni-foil interlayer.

► A suitable welding structure with a steel-on-aluminium overlap joint was used.
► The quality of Fe/Al laser welding was improved via a Ni-foil interlayer.
► A new intermetallic compound Al0.9Ni1.1 was discovered in Fe/Al laser welding.