Mechanism Of Laser Cavitation Strengthening Of 2A02 Aluminum Alloy And Experimental Study On The Effect Of Hydroxyl Radical

Cavitation is a special phenomenon in hydraulic machinery that generally causes serious damage, and even leads to serious accidents. However, the micro-jet and shockwaves urged researchers to develop the study of the cavitation peening by using the extreme physical conditions. Due to laser-induced bubbles with highly spherical,easy to control, the research of cavitation bubbles produced by laser has gradually been becoming an important experimental method to study the cavitation. In the present paper, the effect laser energy and defocusing amount on mechanical properties of 2A02 target through the experimental method, and verify the laser cavitation will generated hydroxyl radicals, Then explore the influence of laser energy and defocusing amount on hydroxyl radicals, hydroxyl radicals as the characteristics of the intensity of laser cavitation is used to characterize the effect laser cavitation on the mechanical properties.Ultimately determine the optimal experimental parameters of laser cavitation and the critical value of hydroxyl radicals used to measure the strengthening of 2A02 target surface mechanical properties. Some important results and research achievements are listed as follows:(1) Explored the influence of defocusing amount H on the surface residual stress and surface topography through experimental. Explored the mechanism of micro-jet,shock wave and laser shock to the material, and analyzed the enhancement mechanism.The results show that there are a circular area on the surface of the target, and target material surface residual stress value and the radius of influence area becomes larger as laser energy increased. But target strengthening effect increases firstly and then decrease as H increased. When H=1mm, surface residual has reached the maximum,and surface topography is best, optimized the strengthening effect.(2) Compared with several methods, and ascertained the method to quantitative detection hydroxyl radicals. Ascertained spin trap and its concentration. Proved theideas that laser cavitation will generate hydroxyl radical by observing the change of absorbance value. The interaction of laser plasma and target will also have an effect on hydroxyl radicals by observing the change of absorbance value. Explored the influence of laser energy and defocusing amount on hydroxyl radicals. Hydroxyl radical represents the intensity of laser cavitation. When H is certain, the intensity of laser cavitation accelerating increase with the increase of laser energy; when H=1mm,hydroxyl radicals is the most, and the intensity of laser cavitation is the strongest.(3) Proved the conclusion that laser cavitation can affect the target by analyzing the relationship between hydroxyl radicals and the surface residual stress of 2A02 target.Explored the feasibility that using hydroxyl radicals to characterize the surface properties of 2A02 target, get the critical values C·OH1 represent the surface properties of2A02 target has improved obviously. Only when C·OH>C·OH1, the surface properties of2A02 appeared obviously strengthening effect; when C·OH<C·OH1, the effect is not obviously, even has no effect.