受控激光喷丸强化技术

介绍了一种利用强脉冲激光诱导产生的冲击波压力来进行金属表面改性的新技术——受控激光喷丸强化技术，可以大幅度提高金属材料的疲劳寿命和抗应力腐蚀能力，但疲劳寿命和抗应力腐蚀能力并不总随着喷丸强度的提高而线性增加。最佳的疲劳寿命和抗应力腐蚀能力常出现在特定的残余压应力水平和分布下，也即取决于喷丸参数的最佳组合。由于激光喷丸中工艺参数对喷丸后工件表层的残余应力场有决定性的影响，如何依据已给的疲劳寿命和抗应力腐蚀能力来合理确定喷丸强化的工艺参数成为目前主要的研究方向。受控激光喷丸的机理与残余应力的形成过程密切相关。首先在理论上研究了影响残余应力分布的激光喷丸工艺参数，如激光功率密度、脉冲宽度、光斑直径等，以及这些参数和残余应力层深度的关系。然后采用QT700-2试样进行激光喷丸强化对比实验，对激光喷丸后的残余应力场大小及其分布进行了无损检测。结果表明，在激光喷丸强化工件时，残余压应力层厚度存在一个最佳值，此时金属表面的疲劳性能和抗应力腐蚀性最优，喷丸工艺参数也达到一个最佳组合。

Controlled Laser Shock Peening Technology

A new technology-controlled laser shock peening which is applied by using a high energy pulsed laser to induce a high amplitude shock wave to make surface modified is introduced. It can improve fatigue life, corrosion and wear resistance of metal part. The fatigue life and the corrosion resistance do not always increase with laser shock peening intensity linealy. Optimal fatigue life and corrosion resistance depend on magnitude and distribution of residual compressive stress, and influence by optimization of various laser processing parameters. Laser processing parameters have a crucial effect on residual stress. Selecting laser processing parameters according to preconcerted fatigue life and corrosion resistance becomes a present subject. Laser shock peening mechanism has a significant relation with the generation of residual stress. In this work, the effect of laser processing parameters such as laser power density, laser beam diameter, laser pulse width on distribution of residual stress, and the relationship between these parameters and residual stress depth are examined. Specimens of QT700-2 are used in this investigation. The magnitude and distribution of the residual stress are measured by using an automatic X-ray diffraction technique. It is observed that while residual compressive stress induced by laser shock peening reach an optimal level, the surface of metal part can obtain optimal fatigue life and corrosion resistance, then optimal combination of laser processing parameters can also be obtained.