Laser lap welding quality of steel/aluminum dissimilar metal joint and its electronic simulations

This paper presents an effect of alloying elements on brittleness of FeAl phase. Microstructure and mechanical properties of laser welding joints with/without Cu or Pb foil in an overlap steel-on-aluminum configuration are investigated. A good agreement between the experimental results and theoretical predictions for the improved mechanical properties can be seen. In the case of adding Pb foil, there is good combination between the metal of the weld pool and the base aluminum metals, welding defects are uneven, and the layer thickness of intermetallic compounds (IMCs) reduces compared with that of no foil; in addition, Mg2Pb phase is formed at the steel/aluminum interface, and the structure of Mg2Pb is more stable than that of FeAl. Thus, the formation of IMCs is inhibited; hence, mechanical properties of the welding joint are significantly improved.