脉冲激光处理等离子体冲击-空化原理的间接验证和理论应用

Indirect confirmation and theoretical application of plasma shock−cavitation principle of pulsed laser shock

提出等离子体冲击-空化双物理效应耦合强化原理,在液体约束脉冲激光冲击中空化效应存在的合理性有待证实。选择XRD测试方法和较易获得衍射峰的304不锈钢,定量检测和表征单脉冲激光作用区域的残余应力分布。试验结果与文献分析表明,激光冲击强化的不同工艺条件导致等离子体冲击与空化两种应力效应的强度匹配不同,无涂层飞秒激光冲击应力效应的主要来源是空化效应。激光脉冲宽度以及吸收层和约束层等工艺参量的实际作用影响或决定脉冲激光表面处理的材料改性原理。

The coupling strengthening principle of the double physical effect of plasma shock−cavitation was proposed,and the rationality of the cavitation effect in pulsed laser shock treatment under liquid−confined conditions needs to be confirmed urgently.The XRD testing method and 304 stainless steel,which is easy to obtain diffraction peaks,were selected to quantitatively detect and characterize the residual stress distribution in the action area of a single pulse laser beam.The test results and literature analysis show that the different process conditions of laser shock processing bring about different strength matching of the two stress effects of plasma shock and cavitation,and the main source of stress effect of femtosecond laser shock without coating is the cavitation effect.The actual effects of the laser pulse width and other process parameters such as the absorption layer and the constraint layer affect or determine the material modification principle of the pulsed laser surface treatment.