Effect of Prior Surface Textures on the Resulting Roughness and Residual Stress during Bead-Blasting of Electron Beam Melted Ti-6Al-4V
Effect of Prior Surface Textures on the Resulting Roughness and Residual Stress during Bead-Blasting of Electron Beam Melted Ti-6Al-4V
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DOI：
10.3390/cryst12030374
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发表时间：
2022-03
期刊：
影响因子：
2.7
通讯作者：
Mustafa Rifat;S. Basu;Edward C. De Meter;G. Manogharan
中科院分区：
文献类型：
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作者：
Mustafa Rifat;S. Basu;Edward C. De Meter;G. Manogharan
增材制造（AM）部件的精加工是使其具有抗疲劳性能的关键。不幸的是，目前的增材制造工艺自然地促进了表面的各向异性特性，这使得优化精加工工艺变得具有挑战性。在本研究中，探讨了喷丸作为一种精加工电子束熔化（EBM） Ti-6Al-4V的工艺。利用光学轮廓法测量表面纹理和x射线衍射测量残余应力，描述了各向异性粗糙度特性对爆丸力学的影响。研究了由增材制造和电火花加工（EDM）产生的接收表面。可以看出，预处理后的粗糙织构对最终织构和残余应力的影响很大。这些联系是用塑性指数作为控制指标来量化的——粗糙的表面具有更大的塑性指数，这导致其纹理特征的演变相对于经过等效喷丸处理的光滑表面。这种演变的机制是用能量控制的压痕作为一个模型，代表在珠药爆破的单一冲击。可以看出，在接收状态下具有复杂纹理的粗糙表面也会产生复杂的应力状态，与光滑表面相比，在压痕期间具有更大水平的局部拉伸应力。研究人员提出了解决这些问题的方法，这些方法有可能将印刷的非功能表面转变为抗疲劳优化的表面。
The finishing of additive manufactured (AM) components is crucial for endowing them with fatigue resistance. Unfortunately, current AM processes naturally promote anisotropic surface characteristics that make it challenging to optimize finishing processes. In this study, bead-blasting is explored as a process for finishing Electron Beam Melted (EBM) Ti-6Al-4V. The effects of anisotropic roughness characteristics on the mechanics of bead-blasting are delineated using surface texture measurements via optical profilometry and residual stress measurements via X-ray diffraction. As-received surfaces resulting from AM, as well as those that have been Electrical Discharge Machined (EDM), are studied. It is seen that pre-processed roughness textures heavily influence the final textures and residual stresses. These linkages are quantified using a plasticity index as the governing metric—a rougher surface features a larger plastic index, which results in comparatively greater evolution of its texture characteristics than a smoother surface after equivalent bead-blasting treatments. The mechanics of this evolution are delineated using energy-controlled indentation as a model representing a single impact in bead-blasting. It is seen that rougher surfaces featuring complex textures in as-received states also produce complex stress states featuring a greater level of locally tensile stresses during indentation compared with smoother surfaces. Approaches to address these complications are proposed that can potentially transform a printed, non-functional surface into one that is optimized for fatigue resistance.