Orthogonal experiment design together with the analysis of variance was used to examine the processing parameters (laser power, scan speed, layer thickness and hatch spacing) of selective laser melting (SLM) for superior properties of SLM parts, in which nine groups of specimens of Ti‐6Al‐4V were fabricated. The results clarify that the influence sequence of individual parameter on the porosity is laser power > hatch spacing > layer thickness > scan speed. Ultrasonic fatigue tests (20 kHz) were conducted for the SLMed specimens in high‐cycle fatigue (HCF) and very‐high‐cycle fatigue (VHCF) regimes. The S‐N data show that the fatigue strength is greatly affected by the porosity: the group with the smallest porosity percentage having the highest fatigue strength in HCF and VHCF regimes. Then, the tests on the validation group were performed to verify the optimal combination of SLM processing parameters. Moreover, the observations by scanning electron microscopy revealed that fatigue cracks initiate at lack‐of‐fusion defects in the cases of surface and internal crack initiation.

中文翻译：

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选择性激光熔化工艺参数对Ti-6Al-4V高循环和超高循环疲劳行为的影响

正交实验设计和方差分析用于检查选择性激光熔化（SLM）的加工参数（激光功率，扫描速度，层厚度和舱口间距），以确保SLM零件的优异性能，其中9组样品制作了Ti-6Al-4V。结果表明，各个参数对孔隙率的影响顺序为激光功率>舱口间距>层厚>扫描速度。在高周疲劳（HCF）和超高周疲劳（VHCF）方案下对SLM试样进行了超声波疲劳测试（20 kHz）。在小号- ñ数据显示，疲劳强度受孔隙度的影响很大：孔隙率最小的组在HCF和VHCF方案中具有最高的疲劳强度。然后，对验证组进行测试以验证SLM处理参数的最佳组合。此外，通过扫描电子显微镜观察发现，在表面和内部裂纹萌生的情况下，疲劳裂纹是在缺乏熔合缺陷的情况下萌生的。