Author Affiliations
1 School of Mechanical Engineering, Nanjing University of Science and Technology,Nanjing, Jiangsu 210094, China2 National Joint Engineering Laboratory for Numerical Control Forming Technology and Equipment,Nanjing, Jiangsu 210094, Chinashow less
Fig. 1. Ti-6Al-4V powder particle size distribution
Fig. 2. Scan strategy of Zig-Zig
Fig. 3. Ti-6Al-4V alloy formed by SLM. (a) Fatigue specimen; (b) cylindrical drawing specimen
Fig. 4. Stress-strain curves of static tensile specimen before and after 840 ℃/2 h/AC heat treatment
Fig. 5. Fracture surface morphologies of samples after different heat treatments. (a) Untreated; (b) 840 ℃/2 h/AC
Fig. 6. Fatigue life of Ti-6Al-4V alloy under different treatments at a constant stress of 330 MPa
Fig. 7. Fracture surface morphologies of fatigue samples after different treatments. (a) As-built; (b) polished; (c) heated and polished
Fig. 8. Microstructure. (a) OM photo and SEM photo of the untreated sample; (b) OM photo and SEM photo of Ti-6Al-4V after 840 ℃/2 h/AC annealing treatment. In (a) and (b), the α' phase is light and the β phase is dark
Fig. 9. XRD patterns of Ti-6Al-4V samples fabricated by SLM
Fig. 10. Stiffness as a function of cycle number of fatigue life for as-built sample, polished sample and polished sample after heat treatment
Fig. 11. Surface defects of SLM specimen
Fig. 12. Fatigue fracture morphologies of directly formed fatigue specimens with different cycles of fatigue life. (a) Fatigue life is 23397 cycle; (b) fatigue life is 24118 cycle; (c) fatigue life is 24039 cycle; (d) fatigue life is 19934 cycle; (e) fatigue life is 26018 cycle
Fig. 13. Correspondence between initial fatigue cracking defect and fatigue life of polished sample and polished sample after heat treatment
Fig. 14. Three-dimensional morphologies of the scanning line at 180 W and poor overlap defects on the XOY plane. (a) Scanning line in the X direction; (b) scanning line in the Y direction; (c) poor overlap defects on the XOY plane
Composition | Al | V | Fe | C | O | N | H | Mo | Mn | Cu | Sn | Y | Zr | Ti |
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Massfraction /% | 5.5-6.75 | 3.5-4.5 | 0.14 | 0.007 | 0.13 | 0.007 | 0.002 | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 | <0.05 | Bal |
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Table 1. Chemical composition of Ti-6Al-4V alloy power
Laser powerP /W | Velocity v /(mm·s-1) | Scan strategy | Hatching spacingh /μm | Layer thicknessτ /μm | Additionalcontour /μm |
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180 | 1250 | Zig-Zig | 105 | 30 | Inside-75 |
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Table 2. Forming parameters of Ti-6Al-4V alloy produced by SLM
Heat treatment | Rm /MPa | Rp0.2 /MPa | A /% | Z /% |
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SLM | 1130.55 | 1079.44 | 12.73 | 22.49 | 840 ℃/2 h/AC | 971.44 | 948.92 | 18.11 | 28.14 | Reference | 989.8 | 942.7 | 15.6 | 43.6 |
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Table 3. Mechanical properties of Ti-6Al-4V alloy produced by SLM under different heat treatments