Resistance Spot Welding Of Aluminium Alloy For Lightweight Vehicle Body Structure

With the energy crisis and the problem of the greenhouse effect is increasing,environmental pollution is getting more and more attention from all over the world.Solve the problem of Reduce emissions and saving gasoline consumption are the much needed solved problems in Automotive."Lightweight" with using of more aluminum alloy material in the car structure is an important way to achieve this goal.The technologyof Resistance Spot Welding(RSW)is the most widely used in the automotive industry.It is the most efficient and best economic benefits way for aluminum alloy welding use of the original equipment technology,but there are still some problems to be solved in resistance spot welding of aluminum alloy because of some unique properties of aluminum.Therefore,it has significant significance and industrial use value to study on Resistance Spot Welding of Aluminum Alloy.In this paper,for the problems of low joint strength,splashing,stomatal,poor surface quality,low electrode life and poor process stability in resistance spot welding of aluminum alloy,the process tests of 5182-O aluminum alloy was studied by using flat head electrode and another new electrode of multi-ring dome(MRD).The best parameters of the two electrodes were determined by metallographic analysis.And the good joints with the largest nugget diameter and no obvious welding defects were obtained.The static tensile strength,dynamic fatigue strength and microhardness distribution of the nuggets were tested and compared under the optimum parameters.The differences of the stability of the two electrodes were analyzed by scanning electron microscopy(SEM)and energy dispersive spectroscopy(EDS).The results showed that: the joint has higher stability,higher joint strength and smaller dispersion using MRD electrode.The study of electrode life on the two electrodes found that the joint strength and nugget diameter used MRD electrode were more stable during the continuous welding process.The electrode wear and the surface alloying were smaller,and the electrode life of MRD was higher.The surfaces of welding spot and electrode surface were analyzed by SEM and EDS.Results showed that he ring on the surface of MRD not only can break through the oxides layer on the aluminum surface,reduce the contact resistance between the electrode and the material and reduce the heat generated by the contact surface,so that the current distribution evenly,but also can reduce the resistance at the electrode/sheet interface and improve heat transfer between the electrode and aluminum,decrease the temperature of contact surface,reduce the Cu / Al alloying reaction and electrode wear,to improve electrode life and process stability.