de Jesus Joel, Martins Ferreira José António, Borrego Luís, Costa José D, Capela Carlos
Centre for Mechanical Engineering, Materials and Processes (CEMMPRE), Department of Mechanical Engineering, University of Coimbra, 3004-531 Coimbra, Portugal.
Department of Mechanical Engineering, Coimbra Polytechnic-ISEC, Rua Pedro Nunes, 3030-199 Coimbra, Portugal.
Materials (Basel). 2021 Feb 5;14(4):737. doi: 10.3390/ma14040737.
Selective laser melting (SLM) is an additive manufacturing process for producing metallic components with complex geometries. A drawback of this process is the process-inherent poor surface finish, which is highly detrimental in materials submitted to fatigue loading situations. The goal of this work is to analyze the fatigue behavior of Ti-6Al-4V specimens with internal axial channels under the following different conditions: hole drilled, hole as manufactured, and hole threaded M4 × 0.7. All the cases studied showed a lower fatigue performance as compared with solid samples due to the surface roughness and geometry effect that produced a surface stress concentration leading to a reduction in fatigue strength. The fractography revealed that crack initiation occurred from the internal surface in all specimens with internal channel mostly from defects as unfused particles and lack of fusion zones, while for the solid specimens crack initiation was observed from the external surface due to insufficient fusion defect. The application of the Smith-Watson-Topper energy-based parameter was revealed to be a good tool for fatigue life prediction of the different series studied.
选择性激光熔化（SLM）是一种用于制造具有复杂几何形状金属部件的增材制造工艺。该工艺的一个缺点是其固有的表面光洁度较差，这对于承受疲劳载荷的材料极为不利。本研究的目的是分析具有内部轴向通道的Ti-6Al-4V试样在以下不同条件下的疲劳行为：钻孔、制造时的孔以及M4×0.7的螺纹孔。与实心样品相比，所有研究案例均表现出较低的疲劳性能，这是由于表面粗糙度和几何形状效应产生了表面应力集中，导致疲劳强度降低。断口分析表明，所有具有内部通道的试样，裂纹均从内表面开始萌生，主要源于未熔合颗粒和熔合不足区域等缺陷；而对于实心试样，由于熔合不足缺陷，裂纹从外表面萌生。结果表明，基于史密斯-沃森-托珀能量的参数应用是预测所研究不同系列疲劳寿命的良好工具。
