Zhou Jiantao, Han Xu, Li Hui, Liu Sheng, Shen Shengnan, Zhou Xin, Zhang Dongqi
The Institute of Technological Sciences, Wuhan University, South Donghu Road, Wuchang District, Wuhan 430072, China.
Shenzhen Institute of Wuhan University, Keyuan South Road, Nanshan District, Shenzhen 518057, China.
Materials (Basel). 2021 Jan 14;14(2):393. doi: 10.3390/ma14020393.
Laser polishing is a widely used technology to improve the surface quality of the products. However, the investigation on the physical mechanism is still lacking. In this paper, the established numerical transient model reveals the rough surface evolution mechanism during laser polishing. Mass transfer driven by Marangoni force, surface tension and gravity appears in the laser-induced molten pool so that the polished surface topography tends to be smoother. The AlSi10Mg samples fabricated by laser-based powder bed fusion were polished at different laser hatching spaces, passes and directions to gain insight into the variation of the surface morphologies, roughness and microhardness in this paper. The experimental results show that after laser polishing, the surface roughness of and of the upper surface can be reduced from 12.5 μm to 3.7 μm and from to 29.3 μm to 8.4 μm, respectively, due to sufficient wetting in the molten pool. The microhardness of the upper surface can be elevated from 112.3 HV to 176.9 HV under the combined influence of the grain refinement, elements distribution change and surface defects elimination. Better surface quality can be gained by decreasing the hatching space, increasing polishing pass or choosing apposite laser direction.
激光抛光是一种广泛用于提高产品表面质量的技术。然而，对其物理机制的研究仍然不足。本文建立的数值瞬态模型揭示了激光抛光过程中粗糙表面的演变机制。在激光诱导的熔池中，由马兰戈尼力、表面张力和重力驱动的质量传递出现，使得抛光后的表面形貌趋于更光滑。本文对通过激光粉末床熔融制造的AlSi10Mg样品在不同的激光扫描间距、扫描道次和扫描方向下进行抛光，以深入了解表面形貌、粗糙度和显微硬度的变化。实验结果表明，激光抛光后，由于熔池中充分的润湿性，上表面的粗糙度分别可以从12.5μm降低到3.7μm，以及从29.3μm降低到8.4μm。在晶粒细化、元素分布变化和表面缺陷消除的综合影响下，上表面的显微硬度可以从112.3 HV提高到176.9 HV。通过减小扫描间距、增加抛光道次或选择合适的激光方向可以获得更好的表面质量。
