Microstructure and properties of steel-aluminum Cold Metal Transfer joints

B. Mezrag (1) , Frédéric Deschaux-Beaume (1) , Laurent Sabatier (2) , Bertrand Wattrisse (3) , M. Benachour (4)

1 AS - Assemblages Soudés
2 LMA - Laboratoire de Mécanique et d'Acoustique [Marseille]
3 ThM2 - ThermoMécanique des Matériaux
4 Université de Tlemcen

1 mm thick sheets of 6016-T4 aluminum alloy and Zn coated steel were joined in a lap configuration using the Cold Metal Transfer (CMT) welding process with an Al-5Si filler metal and different powers and welding speeds. The formed reaction layer ensuring the bonding between the aluminum melting zone and the steel sheet doesn’t exceed 10 μm in thickness, and is composed of an iron-rich Fe-Al intermetallic on the steel side, and a Fe-Al-Si ternary compound on the aluminum weld side. The current waveform producing the lowest mean electrical power gives the most regular welds with lowest porosity in the melting zone. By optimizing the welding speed with this current waveform, the strength of the assembly under monotonic shear-tensile loading can reach 70% of that of the aluminum base material, and its lifetime under cyclic tensile loading exceeds 104 cycles for a maximal linear loading of 98 N mm−1 and 107 cycles for a maximal linear loading of 42 N mm−1.

Mots clés: dissimilar metal joining; arc welding; steel; aluminum; reaction layer; microstructure; mechanical behavior

Domaines: Mécanique des structures [physics.class-ph]

B. Mezrag, Frédéric Deschaux-Beaume, Laurent Sabatier, Bertrand Wattrisse, M. Benachour. Microstructure and properties of steel-aluminum Cold Metal Transfer joints. Journal of Materials Processing Technology, 2020, 277, pp.116414. ⟨10.1016/j.jmatprotec.2019.116414⟩. ⟨hal-03345667⟩