Effect Of Auxiliary Heat On The Efficiency Of Nanosecond Laser Ablation Of Aluminum Alloy

With the development of laser technology,because of the superiority of high laser energy density,small heat-affected zone,high degree of automation,laser processing technology and gradually replace the traditional processing technology,such as laser cutting,metal welding,laser cladding,laser perforation and other processing technology,in the field of automotive manufacturing,biomedical,metal processing,marine engineering,and aerospace fields have a significant role.In the case of continuous development of society and increasingly competitive market,higher requirements for production efficiency have been put forward,so how to improve the efficiency of laser processing has become a priority.Previous studies have shown that when reasonable auxiliary heating is applied to the target,the utilization of laser energy by the subsequent target can be improved,and the laser ablation efficiency of the target can be improved,thus improving the efficiency of laser processing.In order to improve the efficiency of laser ablation under the condition of applied auxiliary heat,the effect of auxiliary heat on the efficiency of laser ablation of aluminum alloy with nanosecond pulses was investigated from both theoretical and experimental aspects by selecting aluminum alloy 2024 as the research object.To address the problem of the effect of nanosecond pulsed laser on the ablation efficiency of aluminum alloy under auxiliary heat,the thesis established a numerical calculation model based on the basic theories of heat transfer and fluid dynamics,and calculated and analyzed the variation law of the temperature characteristics of the target material with the auxiliary heat temperature and the study of the effect of auxiliary heat on the ablation efficiency.The results show that the auxiliary heat temperature will affect the absorption rate of the target material to the subsequent nanosecond pulse laser,the higher the auxiliary heat temperature of the target material,the greater the absorption rate of the target material to the laser,and therefore the higher the energy utilization rate of the nanosecond pulse laser,which leads to the improvement of the processing efficiency;at the same time,the target material under the auxiliary heat,even if the low energy density nanosecond pulse laser will make the target material quickly warm up to reach the vaporization point,producing shock waves or even phase explosion,making more molten material sputtering and improving the ablation efficiency.Based on the numerical calculation and analysis,an experimental system was established to study the efficiency of nanosecond pulsed laser ablation of aluminum alloy under auxiliary heat,and the study of the efficiency of nanosecond pulsed laser ablation of aluminum alloy under room temperature and different auxiliary heat temperatures was carried out.Based on the damage morphology,ablation pit diameter and depth of aluminum alloy,the variation pattern of its ablation efficiency under auxiliary heat was analyzed.The ablation characteristics of the laser on the aluminum alloy target were studied under the same spot size,power densities of 6.79×10~7W/cm~2,1.27×10~8W/cm~2,1.01×10~9W/cm~2and1.18×10~9W/cm~2nanosecond pulsed lasers,and auxiliary heat temperatures of 500K,600K,700K,800K and 900K.The results show that the auxiliary heat can promote the efficiency of nanosecond laser ablation of aluminum alloy,and with the increase of auxiliary heat temperature,the ablation effect of aluminum alloy target is significantly enhanced,the depth of ablation pit shows an increasing trend,and the mass mobility is improved.When the auxiliary heating temperature reaches 900K,there is an obvious step in the depth of the ablation pit,which is 10 times higher than that at room temperature.These results are in good agreement with the theoretical results.The research work of this paper can provide some theoretical basis and experimental support for the development of laser processing technology and the improvement of laser processing technology.