Research On Laser Additive Repair And Modification Technology Based On Vibration Simulation Working Conditions

With the development of marine resources and the continuous emergence of maritime safety issues,timely and effective online repair technology is an important guarantee for resource development and long-term service of ships.Laser additive repair technology is a fast and effective repair method.However,when the additive repair is performed in the marine environment,it will be affected by wind and waves,tidal low-frequency vibration,and ship hull engine vibration factors,which will reduce the uniformity of the additive structure.The performance of the components deteriorates.Therefore,in this paper,316L stainless steel,which is widely used in the field of marine engineering,is selected as the research material,and the finite element analysis technology is used to obtain the temperature field evolution characteristics of the laser additive process under different vibration conditions;then,the additive repair under different vibration directions is prepared.The sample explored the effect of vibration direction on the structure and performance of the repair layer;in view of the problem of the weakening of the structure and performance of the additive layer under longitudinal vibration,the method of introducing TiN and CeO₂/TiN ultrasonic assisted modification was used to optimize the repair layer Organization,improve performance.The numerical simulation results of the temperature field of laser additive under different vibration directions and vibration frequencies show that vertical vibration has little effect on the temperature field;lateral vibration reduces the temperature of the additive process as a whole and shortens the melting time;longitudinal 1Hz vibration causes The temperature distribution is extremely uneven,the temperature of consecutive nodes is quite different,the existence time of the molten pool at different node positions is different,and the melting process is unstable.In the laser additive repair samples of 316L stainless steel under different vibration directions,the vertical vibration has less effect on the repair parts.However,silicon-rich agglomeration defects appeared in the organization under transverse and longitudinal vibration,and the mechanical properties and corrosion resistance decreased.Among them,the sample under longitudinal vibration decreased the most,and the average hardness decreased to 165.43HV0.3,with a decrease of 18.2%;the elongation rate dropped to 28.64%,and the drop rate was 24.91%;the corrosion potential dropped to-0.2710V,and the corrosion current density increased by an order of magnitude compared with the conventional one,which was 2.5429×10-5 A·cm^-2.TiN modification effectively improves the structure and mechanical properties of the repair layer under longitudinal vibration by increasing the viscosity of the molten pool,and inhibits the generation of defects.With the increase of TiN content,the grain refinement,hardness and wear resistance are improved;The tensile mechanical properties of the samples increase with the increase of TiN content.When the TiN content reaches 5%,the tensile strength reaches 940.87MPa,which is much higher than the tensile strength of the 316L matrix（480MPa）,and the elongation reaches 51.687%,which is obviously excellent.In the matrix（40%）;the increase of TiN content will reduce the corrosion potential of the material,but the corrosion current density is at a lower order of magnitude.The sample modified by CeO₂ and TiN has better overall performance,especially after ultrasonic assist,the average hardness of the modified sample is the highest,reaching 213.35HV_0.3,an increase of 29%;the average friction coefficient is the lowest,0.39;While the tensile strength reached 880MPa,the highest elongation rate of 61.25%was obtained;the corrosion potential was increased to-0.2166V,and the corrosion performance was better than that of samples prepared under conventional conditions.