约束层材料对7075铝合金激光喷丸表面强化的实验研究

Experimental Research on Influence of Restraint Layer Materials on Surface Strengthening of 7075 Aluminum Alloy Laser Shot Peening

目的研究不同约束层材料对激光喷丸表面强化效果的影响。方法将激光喷丸技术应用于7075航空铝合金的表面强化处理,利用自制柔性约束层、K9玻璃和水层作为激光喷丸的约束层材料,对7075-T6铝合金进行激光喷丸处理,通过测量不同约束层激光喷丸后的试样表面显微硬度值来衡量表面强化效果。结果在激光能量为1.6 J、脉宽为10 ns、波长为1064 nm的条件下进行单点单次冲击,自制柔性约束层的表面强化效果最好,能使7075铝合金靶材的表面显微硬度值有效提升了11.62%,并且进行连续激光冲击后,其硬度值提升了18.11%;水层作为约束层的表面强化效果次之,能使7075铝合金靶材的表面显微硬度值提升6.99%,容易造成水花飞溅;K9玻璃作为约束层的表面强化效果最差,其表面显微硬度值仅提升了4.05%,K9玻璃在激光喷丸试验中容易破裂。结论通过对激光喷丸试验的结果进行分析和比较,发现不同约束层材料对7075铝合金表面强化效果影响的机理不同,自制柔性约束层对7075铝合金激光喷丸表面强化效果最显著,且具有工程应用价值。

The work aims to study the influence of different restraint layer materials on surface strengthening effect of laser peening. Laser shot peening technology was applied to strengthen the surface of 7075 aluminum alloy, laser peening experiment of the 7075-T6 aluminum alloy was carried out with self-developed flexible restraint layer, K9 glass, water layer as restraint layer materials, and surface micro-hardness of the laser peened specimens were measured to study surface strengthening effect. Single-point single-pass impact was conducted provided with parameters as follows： laser energy of 1.6 J, pulse width 10 ns and wavelength 1064 nm. Under this circumstance, surface strengthening effect of the self-developed flexible restraint layer was the best, surface microhardness value of the laser peened specimens increased by 11.62%. After continuous laser peening, the sur- face microhardness increased by 18.11%. Surface strengthening effect of the restraint layer made of water layer took second place, surface micro-hardness value of the laser peened specimens increased by 6.99%, and water splash might easily be pro- duced. Surface strengthening effect of the restraint layer made of K9 glass took second place was the worst, surface mi- cro-hardness value increased by 4.05% only, and the K9 glass may be broken easily. Influence mechanism of different restraint layer materials on the strengthening effect of 7075 aluminium alloy is found to be different based on analysis and comparison of laser peening experiment results. The self-developed flexible restraint layer has the best surface strengthening effect on 750 aluminium alloy laser peening and is of engineering application value.