Numerical Analysis on Dynamic Behaviour of Keyhole and Molten Pool during Rotating Laser Welding of Aluminum Alloy
The stirring effect of rotating laser on molten pool can expand the range of laser heat source and effectively inhibit defects such as pores,and improve the quality of joint.Due to physical characteristics of the rotating laser heat source,the dynamic behavior of keyhole and molten pool is more complicated than that of the conventional laser welding.The method of numerical simulation was adopted,and the three-dimensional model of the laser welding was developed,which takes the coupling of keyhole,recoil pressure and molten pool into account.The model can describe the dynamic behavior characteristics of keyholes,fluid flow,and the formation process and mechanism of pores in weld during rotating laser welding.It can be concluded that in conventional laser welding,the keyhole is deep,narrow and in unstable dynamic process,which usually produces bubbles.If the air fails to overflow the molten pool in time,the pores are formed.With the increase of laser rotation frequency,the keyhole becomes shallow and wide,and the dynamic behavior tends to be stable,which can effectively inhibit the formation of pores.
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