| Light alloys and carbon fiber reinforced polymer are widely used in aerospace,automotive and other fields due to their excellent light weight and high strength.The requirements for energy saving and emission reduction in the manufacturing industry have led to an increase in the use of light alloys and composite materials,and a multi-material structure has also appeared in the manufacturing field and developed rapidly.Due to the rapid development of multi-material structures,there is an urgent requirement for a new connection technology of dissimilar materials with two physical and chemical properties of light alloy and composite materials.At present,the connection methods commonly used for lightweight alloys and composite materials are bonding,mechanically connected and mixedly connected,but the adhesive used in the bonding method is susceptible to environmental influences,the failure time of which is difficult to determine,and the mechanical connection causes stress concentration and the like.With the continuous development of technology,the connection strength of light alloys and composite materials has also been put forward higher and higher requirements,which makes the single connection method gradually reach the technical limit,and it is necessary to study the new high-strength connection technology.To this end,this paper takes AZ31 B magnesium alloy and carbon fiber reinforced resin matrix composite as the object,and studies a new technology of laser-arc hybrid welding riveting combined with welding and riveting,and analyzes the welded joint under different welding parameters.The variation of morphology and mechanical properties,as well as the influence of different rivet structures on the morphology,microstructure and mechanical properties of welded joints,provide experience and theoretical support for the application of this new technology.The influence of different welding parameters on the welded joints is as follows: in the laser power of 185 W,current arc 70 A,welding speed 7 r / min,the weld is well formed,while maintaining other parameters,laser power,arc current or the welding speed is increased separately,the weld forming size is gradually increased,and the tensile shear load of the joint is also gradually increased.When the most suitable welding parameters are exceeded(laser power 185 W,current arc 70 A,welding speed 7 r/min),the composite material is affected by heat,which caused its melt and vaporization,and the magnesium alloy and composite material cannot be successfully connected.In addition to the research on the influence of welding parameters,the shape of the welded joint was observed to obtain a simple welding heat source distribution map.Four kinds of rivet structures were used to join the AZ31 B magnesium alloy and the carbon fiber composite material.Firstly,the strength of the welded joint under the straight rivet and the stepped rivet structure was compared.The maximum tensile load of the straight rivet joint was 1236.24 N,and that of ladder rivet joint is 1419.21 N;then the microstructure comparison of three different rivet structures shows that the joint has the strongest tensile shear resistance when the three steps of the rivet structure are 6mm,8mm and 12 mm respectively;observe the microstructure and find that The heat affected zone of the weld is narrow,and the grain remains the grain structure of the original base metal.The joint hardness is tested and the order of Vickers hardness is as follows: weld > base metal > heat affected zone.Finally,elemental analysis was carried out on the contact interfaces of dissimilar materials under the step rivet.The analysis results show that there is no element diffusion at the interface between AZ31 B magnesium alloy rivet and carbon fiber composite,and at the interface between AZ31 B magnesium alloy plate and carbon fiber composite plate,there is a small amount of diffusion of magnesium and aluminum,and might react with carbon in the composite. |
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