Effect of Ni on steel/aluminum resistance spot welding

Taking DC01 steel plate and 5082 aluminum alloy plate as the base material,effects of welding current（9-12 kA） and Ni coated layer on shear strength,normal tensile strength and interfacial phase composition of resistance spot welded joint were studied under conditions of electrode pressure 3 kN,welding time 300 ms and holding time 100 ms. The results showed that nugget size and the strength of the joint increased with the increase of welding current. The shear force of Ni coated steel/aluminum joint was one order of magnitude higher than that of normal tension. Under 10 kA welding current,the shear force and normal tension of Ni coated steel/aluminum joint were significantly higher than those of steel/aluminum direct welding,which was due to the formation of Al₃Ni phase at the steel/aluminum interface,which inhibited the formation of brittle Fe₂Al₅ intermetallic compound.