Finite element analysis of temperature and residual stress profiles of porous cubic Ti-6Al-4V titanium alloy by electron beam melting

doi:10.1016/j.jmst.2020.01.033

Abstract

Abstract:

The temperature and stress profiles of porous cubic Ti-6Al-4V titanium alloy grids by additive manufacturing via electron beam melting (EBM) based on finite element (FE) method were investigated. Three-dimensional FE models were developed to simulate the single-layer and five-layer girds under annular and lateral scanning. The results showed that the molten pool temperature in five-layer girds was higher than that in single-layer grids owing to the larger mass and higher heat capacity. More energies accumulated by the longer scanning time for annular path than lateral path led to the higher temperature and steeper temperature gradient. The thermal stress drastically fluctuated during EBM process and the residual stress decreased with the increase of powder layer where the largest stress appeared at the first layer along the build direction. The stress under lateral scanning was slightly larger but relatively more homogeneous distribution than those under annular scanning. The stress distribution showed anisotropy and the maximum Von Mises stress occurred around the central node. The stress profiles were explained by the temperature fields and grids structure.

Key words: Electron beam melting, Ti-6Al-4V titanium alloy, Porous cubic grids, Finite element analysis, Temperature field, Stress field

Xiaochun He, Yang Li, Yongjie Bi, Xiaomei Liu, Bing Zhou, Shangzhou Zhang, Shujun Li. Finite element analysis of temperature and residual stress profiles of porous cubic Ti-6Al-4V titanium alloy by electron beam melting[J]. J. Mater. Sci. Technol., 2020, 44: 191-200.

Figures/Tables 14

Fig. 1. FE models of porous cubic structures: (a) single-layer FE model, (b) five-layer FE model, (c) annular scanning, (d) lateral scanning, (e, f) points a, b, c, d and P4, P5, P6 paths for analysis of temperature and stress behaviors. a1?a5 represents the points from the first layer to the fifth layer at node a.

Table 1 Process parameters of porous cubic grids by EBM.

Process parameters	Values
Power (W)	100
Speed (mm/s)	200
Beam spot diameter (mm)	0.2
Preheating temperature (°C)	730
Thickness of powder layer (mm)	0.05
Hatching spacing (mm)	0.2
Powder absorptivity	0.3
Density (kg/m³)	4440
Melting point (°C)	1649
Thermal conductivity at 20 °C (W m^-1 °C ^-1)	6.8
Specific heat at 20 °C (J kg^-1 °C^-1)	611
Latent heat of fusion at 20 °C (J/kg)	5.4 × 10⁷
Thermal expansion coefficient at 20 °C (10^-6 °C^-1)	8.4
Poisson’s ratio at 20 °C	0.34
Yield strength at 20 °C (MPa)	920
Young’s modulus at 20 °C (GPa)	109

Fig. 2. Width and depth of molten pool under annular (a) and lateral (b) scanning.

Fig. 3. Temperature distribution under annular (a, b) and lateral (c, d) scanning at point a for single-layer FE models.

Fig. 4. Correlation of temperature, cooling rate and time at point a under annular (a) and lateral (b) scanning for single-layer FE models.

Fig. 5. Temperature field distributions after annular scanning: (a) the first layer, (b) the second layer, (c) the third layer, (d) the fourth layer, (e) the fifth layer.

Fig. 6. Relation of temperature and time at point a with 0.5 s after annular (a) and lateral (b) scanning for five-layer models.

Fig. 7. Temperature gradient distributions along P4 (a), P5 (b), and P6 (c, d) paths just after scanning.

Fig. 8. Von Mises stress distributions of points a, b, c, d, e under annular (a, b) and lateral (c, d) scanning and residual stress values (e, f) in single-layer models.

Fig. 9. Von Mises stress distributions at point a under annular (a) and lateral (b) scanning and residual stress values of points a, b, c, d, e (c, d) for five-layer models.

Fig. 10. Von Mises stress distributions along P6 path under annular and lateral scanning for five-layer models (a) and distortion behavior of porous Ti-6Al-4V prepared by EBM under lateral scanning (b).

Fig. 11. Von Mises stress distributions along P6 path under annular and lateral scanning through changing the power from 100 W to 80 W for five-layer models (a) and the corresponding porous Ti-6Al-4V alloy grids (b).

Fig. 12. Stress distributions along the P4 path for five-layer models after cooling to 730 °C: (a) X direction, (b) Y direction, (c) Z direction.

Fig. 13. Von Mises stress distributions along P4 (a) and P5 (b) paths for five-layer models.

References 31

[1]	M. Naebe, K. Shirvanimoghaddam, Appl. Mater. Today 5 (2016)223-245.
[2]	S.Z. Zhang, C. Li, W.T. Hou, S. Zhao, S.J. Li, J. Mater. Sci. Technol. 32(2016) 1098-1104. DOI URL
[3]	A. Mohammadhosseini, S.H. Masood, D. Fraser, M. Jahedi, S. Gulizia, Mater. Today: Proc. 4(2017) 8260-8268.
[4]	I. Eldesouky, O. Harrysson, H. West, H. Elhofy, Addit. Manuf. 17(2017) 169-175.
[5]	M. Kaur, K. Singh, Mater. Sci. Eng. C 102 (2019) 844-862. DOI URL
[6]	X. Li, S.L. Ye, X.N. Yuan, P. Yu, J. Alloys. Compd. 772(2019) 968-977. DOI URL
[7]	N. Ahmed, J. Manuf. Process. 42(2019) 167-191. DOI URL
[8]	H. Lee, T.S. Jang, J.H. Song, H.E. Kim, H.D. Jung, Mater. Lett. 185(2016) 21-24. DOI URL
[9]	W. Yuan, W.T. Hou, S.J. Li, Y.L. Hao, R. Yang, L.C. Zhang, Y. Zhu, J. Mater. Sci. Technol. 34(2018) 1127-1131. DOI URL
[10]	B. Vayre, F. Vignat, F. Villeneuve, Proc. CIRP 7 (2013) 264-269. DOI URL
[11]	L.E. Murr, Addit. Manuf. 5(2015) 40-53.
[12]	V. Chastand, P. Quaegebeur, W. Maia, E. Charkaluk, Mater. Charact. 143(2018) 76-81. DOI URL
[13]	T. Persenot, A. Burr, G. Martin, J. Buffiere, E. Maire, Int. J. Fatigue 118 (2019) 65-76. DOI URL
[14]	X.P. Tan, Y.H. Kok, Y.J. Tan, M. Descoins, C.K. Chua, Acta Mater. 97(2015) 1-16. DOI URL
[15]	S.Y. Liu, Y.C. Shin, Mater. Des. 164(2019) 1-23.
[16]	P. Promoppatum, R. Onler, S.C. Yao, J. Mater. Process. Technol. 240(2017) 262-273. DOI URL
[17]	H.S. Tran, J.T. Tchuindjang, H. Paydas, A. Mertens, A.M. Habraken, Mater. Des. 128(2017) 130-142. DOI URL
[18]	Q.C. Yang, P. Zhang, L. Cheng, Z. Min, A.C. To, Addit. Manuf. 12(2016) 169-177.
[19]	W. Rae, Z. Lomas, M. Jackson, S. Rahimi, Mater. Charact. 132(2017) 10-19. DOI URL
[20]	J. Cao, M.A. Gharghouri, P. Nash, J. Mater. Process. Technol. 237(2016) 409-419. DOI URL
[21]	C. Li, Z.Y. Liu, X.Y. Fang, Y.B. Guo, Proc. CIRP 71 (2018) 348-353. DOI URL
[22]	Z. Luo, Y.Y. Zhao, Addit. Manuf. 21(2018) 318-332.
[23]	X.P. Tan, Y.H. Kok, Y.J. Tan, G. Vastola, C.K. Chua, J. Alloys. Compd. 646(2015) 303-309. DOI URL
[24]	Y. Huang, L.J. Yang, X.Z. Du, Y.P. Yang, Int. J. Therm. Sci. 104(2016) 146-157. DOI URL
[25]	J. Romano, L. Ladani, J. Razmi, M. Sadowski, Addit. Manuf. 8(2015) 1-11.
[26]	G. Vastola, G. Zhang, Q.X. Pei, Y.W. Zhang, Addit. Manuf. 12(2016) 231-239.
[27]	A.S. Wu, D.W. Brown, M. Kumar, G.F. Gallegos, W.E. King, Metall. Mater. Trans. A 45 (2014) 6260-6270. DOI URL
[28]	M. Boivineau, C. Cagran, D. Doytier, V. Eyraud, M.-H. Nadal, B. Wilthan, G. Pot-tlacher, Int. J. Thermophys. 27(2006) 507-529. DOI URL
[29]	E. Kaschnitz, P. Reiter, J.L. Mcclure, Int. J. Thermophys. 23(2002) 267-275. DOI URL
[30]	J.L. Bartlett, X.D. Li, Addit. Manuf. 27(2019) 131-149.
[31]	D.J. Smith, G. Zheng, P.R. Hurrell, C.M. Gill, E. Kingston, Inter. J. Press. Vessels Piping 120-121(2014) 66-79.