Study On Friction Stud Welding Of Dissimilar Material Aluminum Plate/steel Stud

In view of very little study on the Process of friction stud welding at home and abroad,the short life of aluminum stud,and the difficulties of dissimilar metal aluminum/steel welding,this paper studied on process of friction stud welding of dissimilar material aluminum plate/steel stud.According to analysis of the samples’ appearance,tensile properties,fracture morphology,micro-hardness,micro-structure,SEM and EDS,the basic characteristics of friction stud welding of aluminum plate/steel stud were obtained.Homogenous aluminum alloy friction stud welding experimental results showed that the rotation rate,friction time,forging force and other parameters,had a great impact on flash diameter and secondary friction interface layer thickness.The weakest section was combined with secondary friction interface zone of plastic fracture and weak binding zone of brittle fracture.The proportion of plastic fracture zone increased greatly and even the joints as strong as base metal were obtained,with preheating and other reasonable parameters.Orthogonal experiments of friction stud welding of Aluminum plate/steel stud showed that the optimal parameter combination was A2B1C1D2,namely the rotation rate 3 s,friction time 2100r/min,forging force 80MPa,work speed 0.2mm/s.Factor A(rotation rate)and factor B(friction time)on the strength index was not significant,factor C(forging force)and factor D(feed rate)on the strength index was more significant.The experimental results of friction stud welding of Aluminum plate/steel stud with different end face structures showed that the maximum bearing capacity of joints increases with the increasing diameter.Mechanical "bite" effect of wavy interface,combined with the metallurgical reaction,improved the mechanical properties of the joints.The larger diameter interface had a greater depth of Fe-Al diffusion.The weakest section of joints was combined with the C enrichment at Al side of the friction interface and Al rich Fe-Al inter-metallic compound because Fe,C atomic diffusion capacity was higher than Al atomic,rather than the secondary friction interface layer of homogenous material joints.The experimental results of the friction stud welding process with middle layer showed that the tensile strength increases first and then decreases with the increasing thickness of the middle layer.The maximum increase of the tensile strength was about 30%,reaching 93%of base material aluminum.The joint with Cu middle layer was divided into BM-Fe,BM-Cu,TMAZ(IMC),HAZ,BM-1060 five regions.The width of interface layer gradually increased from 210μm to 470μm along the radial direction.The Cu middle layer significantly flowed to the surrounding area under the extrusion force and centrifugal force,and it had a significant inhibitory effect on the Fe-Al intermediate phase.However,the weakest section of joints was combined with the micro holes at the interface and the 100μm thick AlCu inter-metallic compound layer which had cliff-like micro crack with micro-hardness 500HV.