Flow characteristic and solidification behavior in laser wire deposition with assistance of ultra-high frequency induction (UHF)

UHF induction-assisted laser (UHFIAL) deposition is extensively regarded as an effective method in suppressing defects which causes by concentrated thermal input. The introduced induction heat not only can alleviate the temperature gradient of the molten pool but also refine the grain size of microstructure. To further understand the complicated influence mechanism of contactless induction heat on the hybrid deposition, a 3D numerical model coupled with multi-physical fields such as heat transfer, fluid flow, composition transport is developed. The results show that the induction heat slightly increases the maximum temperature of the molten pool and plays a role in slow-cooling effect for the deposited track. The electromagnetic stirring effect derived from electromagnetic force alters the flow pattern of the liquid metal, accelerating the flow velocity of the molten metal in the molten pool. Research on the inductive heating parameters indicates that increasing the current intensity/frequency can improve the maxim temperature of the molten pool and accelerate the flow velocity of the molten metal. The grain morphology and trends in the microstructure evolution can be effectively predicted by combining of cooling rate G*R and shape control factor K, which is experimentally and numerically validated. Under the action of electromagnetic stirring, increasing the current frequency/intensity can both effectively refine the grain size of microstructure. The samples exhibit better wear performance due to fine grain strengthening.