Longitudinal Compression Behavior of Functionally Graded Ti-6Al-4V Meshes

doi:10.1016/j.jmst.2016.02.008

Abstract

Abstract:

The compressive deformation behavior in the longitudinal direction of graded Ti-6Al-4V meshes fabricated by electron beam melting was investigated using experiments and finite element methods (FEM). The results indicate that the overall strain along the longitudinal direction is the sum of the net strain carried by each uniform mesh constituent and the deformation behavior fits the Reuss model well. The layer thickness and the sectional area have no effect on the elastic modulus, whereas the strength increases with the sectional area due to the edge effect of each uniform mesh constituent. By optimizing 3D graded/gradient design, meshes with balanced superior properties, such as high strength, energy absorption and low elastic modulus, can be fabricated by electron beam melting.

Key words: Graded Ti-6Al-4V meshes, Electron beam melting, Reuss model, Compressive deformation, Edge effect

Zhang Shangzhou,Li Cong,Hou Wentao,Zhao Shuo,Li Shujun. Longitudinal Compression Behavior of Functionally Graded Ti-6Al-4V Meshes[J]. J. Mater. Sci. Technol., 2016, 32(11): 1098-1104.

Figures/Tables 13

Fig. 1. Models of three-layer (a) and four-layer (b) graded meshes designed by Materialise/Magics software. The strength and Young's modulus of the uniform mesh constituent decreased in order of G5 > G4 > G3 > G2 > G1.

Table 1. Chemical compositions of Ti-6Al-4V ELI powders (in wt%)

Al	V	Fe	O	N	Ti
6.04	4.05	0.07	0.13	0.005	Bal.

Fig. 2. Macroscopic image of three-layer graded meshes (a) and SEM images of mesh struts (b).

Fig. 3. OM (a) and SEM (b) microstructure of mesh strut.

Fig. 4. Typical loading and unloading stress-strain curves recorded by the strain extensometer to estimate static modulus of three-layer graded meshes designed according to Fig. 1(a).

Table 2. Experimental and calculated elastic moduli of uniform and graded meshes (GPa)

Layers	Uniform meshes					Graded meshes
	Uniform meshes					Experimental	Calculated
	G1	G2	G3	G4	G5	/	/
Three	0.132	/	0.233	/	0.434	0.211	0.236
Four	0.132	0.179	/	0.308	0.434	0.213	0.229

Fig. 5. Compressive nominal stress-strain curves of uniform and graded meshes: (a) three-layer graded meshes; (b) four-layer graded meshes.

Fig. 6. Images of three-layer graded Ti-6Al-4V mesh at strains of 0% (a), 6% (b), 11.5% (c) and 16.5% (d) during longitudinal compression, which were recorded by videos.

Table 3. Experimental and calculated yield strength of uniform and graded meshes (MPa)

Layers	Uniform meshes					Graded meshes
	Uniform meshes					Experimental	Calculated
	G1	G2	G3	G4	G5	/	/
Three	5.28	/	7.69	/	11.72	7.17	7.41
Four	5.28	6.47	/	8.95	11.72	7.26	7.39

Fig. 7. Compressive stress-strain curves of three-layer graded meshes with different layer thicknesses at a sectional area of 30 mm × 30 mm.

Fig. 8. Compressive stress-strain curves of three-layer graded meshes with different sectional areas at a height of 10 mm.

Fig. 9. Effective stress maps of three-layer graded meshes with layer thicknesses of 10 mm (a), 15 mm (b), and 20 mm (c).

Fig. 10. Effective displacement (Y axis) maps of three-layer graded meshes with layer thicknesses of 10 mm (a), 15 mm (b), and 20 mm (c).

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