Effects of Milling on Surface Integrity and Fatigue Performance of TC4 Titanium Alloy by SLM

doi:10.3969/j.issn.1004-132X.2023.02.011

Abstract

Abstract: Aiming atthe problems of poor surface quality and low fatigue performance of TC4 titanium alloys by SLM， the influences of the milling processes on the surface integrity and fatigue performance of the additive parts were studied by three-point bending fatigue tests of additive parts before and after milling. The results show that after milling， the surface roughness Ra of the additive parts is reduced from 12.57 μm to 0.32 μm， the surface hardness is increased from 353. 0HV to 434.3HV， fatigue life of additive parts is increased from 48 272 cycles to 155 463 cycles. After milling， the location of fatigue source of additive parts is transferred from the surface and subsurface to the interior of the specimen， and the fatigue fracture mode is changed from quasi-dissolution fracture to ductile fracture. The surface integrity of the milled specimens is greatly improved， the fatigue crack emergence and expansion of surface fatigue cracks are suppressed， and the fatigue performance is significantly improved after milling of the additive parts.

Key words: selective laser melting（SLM）, titanium alloy, milling, surface integrity, fatigue life

摘要： 针对激光选区熔化（SLM）成形TC4钛合金表面质量差和疲劳性能低等问题，采用三点弯曲疲劳试验测试了铣削前后增材件的疲劳性能，研究了铣削工艺对增材件表面完整性和疲劳性能的影响规律。结果表明，增材件经过铣削加工后，表面粗糙度Ra由12.57 μm降至0.32 μm；表面硬度由353.0HV提高至434.3HV；疲劳寿命由48 272周次提高至155 463周次，疲劳源萌生位置由表面及次表面转移至内部，疲劳断裂模式由准解理断裂过渡到韧性断裂。增材件经铣削加工后，表面完整性得到极大的改善，可抑制疲劳裂纹的萌生和扩展，疲劳性能得到显著提升。

关键词: 激光选区熔化, 钛合金, 铣削, 表面完整性, 疲劳寿命

CLC Number:

V216.3

JI Wenbin, DENG Riqing, DAI Shijie, LIU Chuncheng. Effects of Milling on Surface Integrity and Fatigue Performance of TC4 Titanium Alloy by SLM[J]. China Mechanical Engineering, 2023, 34(02): 208-217,225.

季文彬, 邓日清, 戴士杰, 刘春成. 铣削对SLM增材TC4钛合金表面完整性和疲劳性能的影响[J]. 中国机械工程, 2023, 34(02): 208-217,225.

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