Refill friction spot welding process for aluminium-lithium alloy

Mechanical parameters of spot-welded structure of 22MnB5 ultra-high strength steel were obtained by a series of experiments including tensile-shear testing,optical experiment and the vickers-hardness testing.In addition,intensity simulations on the spot-welded structure were carried out by software ANSYS.The good agreement of simulation results with experimental data confirmed the rationality of the three-phrase finite element model of the spot-welded structure,which consist of weld nugget,plastic ring and base metal.Based on the simulation results, the plastic ring edge of the spot-welded structure interface is the weakest position,where the structural failure is mainly caused by the shear stress.For purpose of spot-welded structure optimization,the dependence of strength of the spot-welded structures on their structure parameters were analyzed.The simulations results uncovered that the maximum Von Mises stress of the structure can be reduced to a considerable extent by increasing radius of the weld nugget,the overlapping length of the two sheets and the thickness of the plates.