Welding Properties Of High Strength Steel Andaluminum Alloy

In recent years, Environmental issues has caused various academic and industrialtechnicians’ research boom on automotive lightweight technology. Studies have shownthat substitution of thin high strength steel and lightweight aluminum alloy compositestructure for traditional steel structure can effectively reduce vehicle weight. However,due to the mechanical connection of dissimilar metals, adhesives and other connectivitytechnologies in strength, performance areas unable to meet industrial needs, weldingperformance between the two is bound to receive widespread attention. Due to widedifferences on the their properties, welding problem between steel and aluminum hasbeen a diffculty in welding areas. What is more, it is easy to produce britle compmand tohave an effect on the welding stremgth.In this paper, high strength steel for automobile body and6061aluminum alloy wereused for the base material, pretreatment technology of this high strength steel werestudied to get a good transition layer, so that it will be a barrier in thewelding process.there are there parts in this study：Firstly, the activation process on thesurface of high strength steel was studied. The results showed that, the act-ivation canchange the steel surface conditions, and different activation concentrationand activation time have effect on activation effect. Then, activation of hot dipaluminizing process of high strength steel was studied. Research showed that, differentactivation time and aluminizing time has influence on the formation of the aluminizedlayer, when the activation is14s, and hot dipping is80s, the best aluminum layer was got.Finally, the aluminized high strength steel and aluminum alloy was welded by orthogonaltest. Experimental results showed that, the activation time and aluminizing time effect onthe joint strength is more significant, the optimal combination is as follows:the activation of14s, hot-dipping80s processing, welding peak current80A, the weldingspeed0.8m/min, at this time, the tensile shear strength can reach136.4N/mm. Theanalysis of joint fracture analysis and metallographicshowed the jonit has formed agood metallurgical combination. The SEM, XRD and other related analysis can provedthat new phase of Al65Cu20Fe15and Al3Ni was the reason of high strength of the joints.