In Situ Elimination of Pores During Laser Powder Bed Fusion of Ti-6.5Al-3.5Mo-l.5Zr-0.3Si Titanium Alloy

doi:10.1007/s40195-021-01297-z

Abstract

Abstract:

The printing quality of components manufactured using laser powder bed fusion (LPBF) generally depends on the presence of various defects such as massive porosity. Thus, the efficient elimination of pores is an important factor in the production of a sound LPBF product. In this study, the efficacy of two in situ laser remelting approaches to eliminating pores during the LPBF of a titanium alloy Ti-6.5Al-3.5Mo-l.5Zr-0.3Si (TC11) was assessed both experimentally and computationally. These two remelting methods are surface remelting and layer-by-layer printing and remelting. A multi-track multi-layer phenomenological model was established to analyze the variation of pores with the temperature and velocity fields. The results showed that surface remelting with a high laser power, such as 180 W, can effectively eliminate pores within three deposited layers. However, such remelting could not reach defects in deeper regions. Layer-by-layer remelting with a 180 W laser could effectively eliminate the pores formed in the previous layer in real time. The results obtained in this study can provide useful guidance for the in situ control of printing defects supported by real-time monitoring, feedback, and operating systems of an intelligent LPBF equipment.

Key words: Laser powder bed fusion, Ti-6.5Al-3.5Mo-l.5Zr-0.3Si, Pores, Laser remelting

Ling Zhang, Wen-He Liao, Ting-Ting Liu, Hui-Liang Wei, Chang-Chun Zhang. In Situ Elimination of Pores During Laser Powder Bed Fusion of Ti-6.5Al-3.5Mo-l.5Zr-0.3Si Titanium Alloy[J]. Acta Metallurgica Sinica (English Letters), 2022, 35(3): 439-452.

Figures/Tables 17

Table 1 Chemical composition of Ti-6.5Al-3.5Mo-l.5Zr-0.3Si powder (wt%)

Ti	Al	Mo	Zr	Si	Fe	C	O	N	H
Bal	6.6	3.2	1.7	0.3	0.08	0.02	0.12	0.006	0.002

Fig. 1 SEM image of Ti-6.5Al-3.5Mo-l.5Zr-0.3Si powder

Table 2 Process parameters used for multi-track multi-layer LPBF of TC11

Samples	Laser power (W)	Velocity (m/s)	Hatching spacing (μm)	Tracks	Layers
No. 1	90	1.25	90	5	1
No. 2	120	1.25	90	5	1
No. 3	150	1.25	90	5	1
No. 4	180	1.25	90	5	1
No. 5	90	1.25	90	5	5

Table 3 Process parameters used for laser remelting

Samples	Laser power (W)	Velocity (m/s)	Hatching spacing (μm)	Remelting strategy
No. 6	120	1.25	90	SR
No. 7	150	1.25	90	SR
No. 8	180	1.25	90	SR
No. 9	120	1.25	90	LR
No. 10	150	1.25	90	LR
No. 11	180	1.25	90	LR

Fig. 2 Schematic diagram of laser powder bed fusion and laser remelting: a laser powder bed fusion, b surface melting, and c layer-by-layer remelting. The red cuboid represents the laser remelting layer and the blue cuboid represents the laser powder bed fusion layer

Fig. 3 Translations of multi-track and multi-layer LPBF

Table 4 Thermophysical properties of TC11 in the low-temperature zone [51]

Temperature (K)	300	400	500	600	700	800	1570	1640	2000
Specific heat (J kg^-1 K^-1)	605	654	712	766	795	840	1210	1238	1412
Temperature (K)	107	200	303	414	504	600	709	797	890
Thermal conductivity (W m^-1 K^-1)	6.3	7.5	9.2	10.5	12.1	13.0	14.2	15.5	17.2

Table 5 Thermophysical properties of TC11 and Ar used in the calculations [52]

Parameters	Values
Density of metal (kg m^-3)	4480
Solidus temperature (K)	1844
Liquidus temperature (K)	1914
Evaporation temperature (K)	3494
Viscosity of liquid metal (Pa s)	4 \(\times \) 10^-3
Temperature coefficient of surface tension (N m^-1 K^-1)	- 2.6 \(\times \) 10^-4
Latent heat of fusion (J kg^-1)	2.86 \(\times \) 10⁵
Latent heat of evaporation (J kg^-1)	9.8 \(\times \) 10⁶
Gas constant (J kg^-1 mol^-1)	8.314
Stefan-Boltzmann constant (W m^-2 K^-4)	5.67 \(\times \) 10^-8
Thermal conductivity of Ar (W m^-2 K^-1)	1.772
Specific heat of Ar (J kg^-1 K^-1)	521.75
Viscosity of Ar (Pa s)	2.2 \(\times \) 10^-5

Fig. 4 Temperature field and molten pool morphology of the deposited tracks at different moments: a 520 µs, b 1320 µs, c 2160 µs, d 2920 µs, and e 3760 µs. Laser power: 90 W, scanning speed: 1.25 m/s

Fig. 5 Temperature field longitudinal sections of multi-track LPBF under different laser powers: a, b 90 W, c, d 120 W, e, f 150 W, and g, h 180 W. Scanning speed: 1.25 m/s

Fig. 6 Dimensions of the molten pool under different laser powers: a 90 W, b 120 W, c 150 W, and d 180 W. Scanning speed: 1.25 m/s

Fig. 7 Experimental results of five-track and five-layer LPBF: a surface topography and b transverse section topography. Laser power: 90 W, scanning speed: 1.25 m/s

Fig. 8 Transverse section topographies of surface remelting under different laser powers: a 120 W, b 150 W, and c 180 W, respectively. Scanning speed: 1.25 m/s

Fig. 9 Temperature field longitudinal sections of layer-by-layer remelting. a, c, e laser power: 90 W, LPBF with a new powder layer and b, d, f laser power: 180 W, laser melting without a new powder layer. Scanning speed: 1.25 m/s

Fig. 10 Evolution of pores during remelting: a 0 µs, b 21 µs, c 37 µs, d 53 µs, e 67 µs, f 83 µs, g 95 µs, h 101 µs, i 135 µs, j 151 µs, k 185 µs, and l 985 µs

Fig. 11 Transverse section topographies of a layer-by-layer remelting with five tracks and five layers. Experimental results under different laser powers: a 120 W, b 150 W, and c 180 W; Simulation results under different laser powers: d 120 W, e 150 W, and f 180 W. Scanning speed: 1.25 m/s. Inside the red dashed line lies the laser scanning area, outside the red dotted line lies the powder area

Fig. 12 Transverse section topographies of a layer-by-layer remelting with thirty layers under different laser powers: a 120 W, b 150 W, and c 180 W. Scanning speed: 1.25 m/s

References 61

[1]	S.M. Thompson, L. Bian, N. Shamsaei, A. Yadollahi, Addit. Manuf. 8, 36 (2015)
[2]	K. Wei, M. Lv, X. Zeng, Z. Xiao, G. Huang, M. Liu, J. Deng, Mater. Charact. 150, 67 (2019) DOI URL
[3]	S.E. Brika, M. Letenneur, C.A. Dion, V. Brailovski, Addit. Manuf. 31, 100929(2020)
[4]	N. Shamsaei, A. Yadollahi, L. Bian, S.M. Thompson, Addit. Manuf. 8, 12 (2015)
[5]	A.A. Martin, N.P. Calta, S.A. Khairallah, J. Wang, P.J. Depond, A.Y. Fong, V. Thampy, G.M. Guss, A.M. Kiss, K.H. Stone, C.J. Tassone, J. Nelson Weker, M.F. Toney, T. van Buuren, M.J. Matthews, Nat. Commun. 10, 1987 (2019)
[6]	Y.N. Hu, S.C. Wu, Z.K. Wu, X.L. Zhong, S. Ahmed, S. Karabal, X.H. Xiao, H.O. Zhang, P.J. Withers, Int. J. Fatigue 136, 105584 (2020)
[7]	S. Liu, Y.C. Shin, Mater. Des. 164, 107552(2019)
[8]	A. Fatemi, R. Molaei, N. Phan, Int. J. Fatigue 134, 105479 (2020)
[9]	J.W. Pegues, S. Shao, N. Shamsaei, N. Sanaei, A. Fatemi, D.H. Warner, P. Li, N. Phan, Int. J. Fatigue 132, 105358 (2020)
[10]	R. Molaei, A. Fatemi, N. Sanaei, J. Pegues, N. Shamsaei, S. Shao, P. Li, D.H. Warner, N. Phan, Int. J. Fatigue 132, 105363 (2020)
[11]	J. Zhang, A. Fatemi, Int. J. Fatigue 103, 102260 (2019)
[12]	N. Sanaei, A. Fatemi, Mater. Sci. Eng. 785, 139385(2020)
[13]	M. Suraratchai, J. Limido, C. Mabru, R. Chieragatti, Int. J. Fatigue 30, 2119 (2008)
[14]	Y. Chen, S.J. Clark, C.L.A. Leung, L. Sinclair, S. Marussi, M.P. Olbinado, E. Boller, A. Rack, I. Todd, P.D. Lee, Appl. Mater. Today 20, 100650 (2020)
[15]	Y. Shi, K. Yang, S.K. Kairy, F. Palm, X. Wu, P.A. Rometsch, Mater. Sci. Eng. 732, 41 (2018) DOI URL
[16]	H. Gong, K. Rafi, H. Gu, G.D. Janaki Ram, T. Starr, B. Stucker , Mater. Des. 86, 545 (2015) DOI URL
[17]	T. Yang, T. Liu, W. Liao, E. MacDonald, H. Wei, C. Zhang, X. Chen, K. Zhang, J. Alloys Compd. 849, 156300(2020)
[18]	G. Kasperovich, J. Haubrich, J. Gussone, G. Requena, Mater. Des. 105, 160 (2016) DOI URL
[19]	M. Tang, P.C. Pistorius, J.L. Beuth, Addit. Manuf. 14, 39 (2017)
[20]	H.L. Wei, Y. Cao, W.H. Liao, T.T. Liu, Addit. Manuf. 34, 101221(2020)
[21]	X. Zhou, D. Wang, X. Liu, D. Zhang, S. Qu, J. Ma, G. London, Z. Shen, W. Liu, Acta Mater. 98, 1 (2015) DOI URL
[22]	R. Priya Parida, V. Senthilkumar, Mater. Today Proc. 39, 1372 (2021)
[23]	A.A. Martin, N.P. Calta, J.A. Hammons, S.A. Khairallah, M.H. Nielsen, R.M. Shuttlesworth, N. Sinclair, M.J. Matthews, J.R. Jeffries, T.M. Willey, J.R.I. Lee, Mater. Today 1, 100002 (2019)
[24]	Y.N. Hu, S.C. Wu, P.J. Withers, J. Zhang, H.Y.X. Bao, Y.N. Fu, G.Z. Kang, Mater. Des. 192, 108708(2020)
[25]	H. Masuo, Y. Tanaka, S. Morokoshi, H. Yagura, T. Uchida, Y. Yamamoto, Y. Murakami, Int. J. Fatigue 117, 163 (2018)
[26]	S. Bagehorn, J. Wehr, H.J. Maier, Int. J. Fatigue 102, 135 (2017)
[27]	P. Li, D.H. Warner, A. Fatemi, N. Phan, Int. J. Fatigue 85, 130 (2016)
[28]	M. Tarik Hasib, H.E. Ostergaard, X. Li, J.J. Kruzic, Int. J. Fatigue 142, 105955 (2021)
[29]	S. Leuders, M. Thöne, A. Riemer, T. Niendorf, T. Tröster, H.A. Richard, H.J. Maier, Int. J. Fatigue 48, 300 (2013)
[30]	B. Vrancken, L. Thijs, J.-P. Kruth, J. Van Humbeeck, J. Alloys Compd. 541, 177 (2012) DOI URL
[31]	S.M.H. Hojjatzadeh, N.D. Parab, Q. Guo, M. Qu, L. Xiong, C. Zhao, L.I. Escano, K. Fezzaa, W. Everhart, T. Sun, L. Chen, Int. J. Mach. Tools Manuf. 153, 103555(2020)
[32]	R. Cunningham, A. Nicolas, J. Madsen, E. Fodran, E. Anagnostou, M.D. Sangid, A.D. Rollett, Mater. Res. Lett. 5, 516 (2017) DOI URL
[33]	S.M.H. Hojjatzadeh, N.D. Parab, W. Yan, Q. Guo, L. Xiong, C. Zhao, M. Qu, L.I. Escano, X. Xiao, K. Fezzaa, W. Everhart, T. Sun, L. Chen, Nat. Commun. 10, 3088 (2019) DOI PMID
[34]	S. Tammas-Williams, P.J. Withers, I. Todd, P.B. Prangnell, Scr. Mater. 122, 72 (2016) DOI URL
[35]	J.T. Hofman, B. Pathiraj, J. van Dijk, D.F. de Lange, J. Meijer, J. Mater. Process. Technol. 212, 2455 (2012) DOI URL
[36]	S. Huang, R.L. Narayan, J.H.K. Tan, S.L. Sing, W.Y. Yeong, Acta Mater. 204, 116522(2021)
[37]	M. Cabeza, G. Castro, P. Merino, G. Pena, M. Román, Surf. Coat. Technol. 212, 159 (2012) DOI URL
[38]	Z. Xiang, R. Yan, X. Wu, L. Du, Q. Yin, Optik 206, 164316 (2020)
[39]	B. Shen, H. Li, S. Liu, J. Zou, S. Shen, Y. Wang, T. Zhang, D. Zhang, Y. Chen, H. Qi, J. Alloys Compd. 818, 152845(2020)
[40]	E. Yasa, J. Deckers, J. Kruth, Rapid Prototyp. J. 17, 312 (2011) DOI URL
[41]	B. Liu, B.-Q. Li, Z. Li, Results Phys. 12, 982 (2019) DOI URL
[42]	W. Yu, S.L. Sing, C.K. Chua, X. Tian, J. Alloys Compd. 792, 574 (2019) DOI URL
[43]	Z. Xiao, C. Chen, Z. Hu, H. Zhu, X. Zeng, Opt. Laser Technol. 122, 105890(2020)
[44]	H.L. Wei, T. Mukherjee, W. Zhang, J.S. Zuback, G.L. Knapp, A. De, T. DebRoy, Prog. Mater. Sci. 116, 100703(2021)
[45]	H. Gu, C. Wei, L. Li, Q. Han, R. Setchi, M. Ryan, Q. Li, Int. J. Heat Mass Transf. 151, 119458(2020)
[46]	Z. Wang, W. Yan, W.K. Liu, M. Liu, Comput. Mech. 63, 649 (2018) DOI URL
[47]	T. Mukherjee, H.L. Wei, A. De, T. DebRoy, Comput. Mater. Sci. 150, 304 (2018) DOI URL
[48]	T. Mukherjee, H.L. Wei, A. De, T. DebRoy, Comput. Mater. Sci. 150, 369 (2018) DOI URL
[49]	H.L. Wei, S. Pal, V. Manvatkar, T.J. Lienert, T. DebRoy, Scr. Mater. 108, 88 (2015) DOI URL
[50]	J.C. Cano-Lozano, R. Bolaños-Jiménez, C. Gutiérrez-Montes, C. Martínez-Bazán, Appl. Math. Model. 39, 3290 (2015) DOI URL
[51]	E.E. B, Engineering Materials Practical Manual (China Standard Press, Beijing, 2002).
[52]	X. Gong, Fundamental Research on Repairing of TC11 Titanium Alloy Blades by Laser Cladding Deposition (General Research Institute for Nonferrous Metals, 2014).
[53]	Y. Zhao, K. Aoyagi, K. Yamanaka, A. Chiba, Addit. Manuf. 36, 101559(2020)
[54]	W. Yan, W. Ge, Y. Qian, S. Lin, B. Zhou, W.K. Liu, F. Lin, G.J. Wagner, Acta Mater. 134, 324 (2017) DOI URL
[55]	C. Tang, J.L. Tan, C.H. Wong, Int. J. Heat Mass Transf. 126, 957 (2018) DOI URL
[56]	K. Darvish, Z.W. Chen, T. Pasang, Mater. Des. 112, 357 (2016) DOI URL
[57]	S.L. Sing, W.Y. Yeong, Virtual Phys. Prototyp. 15, 359 (2020) DOI URL
[58]	X. Zhou, X. Liu, D. Zhang, Z. Shen, W. Liu, J. Mater. Process. Technol. 222, 33 (2015) DOI URL
[59]	D. Zhang, P. Zhang, Z. Liu, Z. Feng, C. Wang, Y. Guo, Addit. Manuf. 21, 567 (2018)
[60]	C. Qiu, Z. Wang, A.S. Aladawi, M.A. Kindi, I.A. Hatmi, H. Chen, L. Chen, Metall. Mater. Trans. A 50, 4423 (2019)
[61]	D. Gu, Y.C. Hagedorn, W. Meiners, G. Meng, R.J.S. Batista, K. Wissenbach, R. Poprawe, Acta Mater. 60, 3849 (2012) DOI URL