Refinement of α′ Martensite by Oxygen in Selective Laser Melted Ti-6Al-4V

doi:10.1007/s40195-023-01657-x

Abstract

Abstract:

Oxygen is crucial in influencing the microstructure evolution of selective laser melted (SLMed) Ti–6Al–4V, significantly impacting its applicability in various sectors. Therefore, this study investigates the influnce of oxygen on microstructure evolution, particularly α′ martensite transformation and refinement mechanisms. Four alloys, Ti–6Al–4V–xO (x = 0.11, 0.16, 0.21, and 0.25 wt%), were fabricated by the SLM process. The martensite start temperature (M_s) of Ti–6Al–4V, as evaluated by computation, is 656.8 °C, and oxygen was found to increase the M_s by about 10 °C per 0.1 wt%. The SLMed alloy samples exhibit [001]_β growth texture along the build direction. Crystallographic analysis of martensite morphology suggests internal twinning on $\left\{ {10\overline{1}1} \right\}$ planes as the lattice invariant strain, which becomes more predominant with increasing oxygen content. Refinement of α′ martensite plates by oxygen is due to increased lattice distortion, reduced prior β grain size, and oxygen segregation to β grain boundaries. Our findings contribute to improving the understanding of the effect of oxygen on the transformation mechanism of α′ martensite during SLM of Ti–6Al–4V.

Key words: Selective laser melting, α′ Martensite, Martensite start temperature, Oxygen, Ti-6Al-4V

Hasfi F. Nurly, Jinhu Zhang, Dechun Ren, Yusheng Cai, Haibin Ji, Dongsheng Xu, Zhicheng Dong, Hao Wang, Qingmiao Hu, Jiafeng Lei, Rui Yang. Refinement of α′ Martensite by Oxygen in Selective Laser Melted Ti-6Al-4V[J]. Acta Metallurgica Sinica (English Letters), 2024, 37(5): 777-792.

Figures/Tables 17

Fig. 1 a Design model, scanning strategies, and as-built material (dimension in mm) of SLMed Ti-6Al-4V. b Morphology of powders and c their size distribution of Ti-6Al-4V-xO

Table 1 Chemical compositions of SLMed Ti-6Al-4V-xO alloys (wt%)

Alloy	Ti	Al	V	O	Fe	H	C	N	Si
TC4-1	Bal	5.86	4.18	0.11	0.032	0.0019	0.0064	0.011	0.01
TC4-2	Bal	5.85	4.18	0.16	0.027	0.0019	0.012	0.0098	0.01
TC4-3	Bal	5.85	4.16	0.21	0.026	0.0017	0.018	0.0093	0.01
TC4-4	Bal	5.95	4.16	0.25	0.022	0.0018	0.023	0.0086	0.01

Table 2 Chemical driving force of the BCC to HCP structural transformation △Gβ→α, the elastic strain energy △GT, the lattice distortion energy due to substitutional elements △Gsubs and due to interstitial elements △Gint at the martensitic start temperature Ms, and β transus Tβ of Ti-Al-V alloys

Alloy composition (wt%)	△G_β_→_α (J/mol)	△G_T (J/mol)	△G_subs (J/mol)	△G_int (J/mol)	M_s (°C)	T_β (°C)
Ti	130.861	130.861	0	0	845.950	882
Ti-1Al	201.404	129.484	71.920	0	848.300	909
Ti-2Al	269.795	128.327	141.468	0	849.400	933
Ti-3Al	336.202	127.296	208.906	0	849.800	956
Ti-4Al	400.776	126.360	274.416	0	849.700	976
Ti-5Al	463.700	125.514	338.186	0	849.100	996
Ti-6Al	525.025	124.728	400.297	0	848.200	1015
Ti-1V	136.676	136.117	0.559	0	813.425	863
Ti-2V	142.599	141.436	1.162	0	780.525	846
Ti-3V	148.568	146.758	1.810	0	747.625	829
Ti-4V	154.584	152.081	2.502	0	714.725	813
Ti-6Al-1V	550.600	130.636	420.013	0	809.900	996
Ti-6Al-2V	580.500	137.522	442.948	0	765.250	978
Ti-6Al-3V	614.200	145.314	468.886	0	714.725	959
Ti-1Al-4V	238.879	151.852	87.0262	0	708.850	837
Ti-2Al-4V	322.032	151.813	170.218	0	701.800	859
Ti-3Al-4V	404.374	151.960	252.414	0	693.575	881
Ti-4Al-4V	486.802	152.471	334.331	0	683.000	901
Ti-5Al-4V	569.883	153.338	416.545	0	670.075	922
Ti-6Al-4V	652.850	154.247	498.603	0	656.800	942
Ti-6Al-4V-0.11O	658.379	152.462	491.803	14.114	668.500	963
Ti-6Al-4V-0.16O	660.397	151.569	488.457	20.371	674.350	973
Ti-6Al-4V-0.21O	662.981	150.826	485.600	26.555	679.225	983
Ti-6Al-4V-0.25O	664.327	150.081	482.836	31.410	684.100	991

Fig. 2 Calculated Ms and Tβ temperatures of a Ti-xAl and Ti-xAl-4V, b Ti-xV and Ti-6Al-xV alloys

Fig. 3 a Variations of the Gibbs free energy of the β and supersaturated α phase of Ti-6Al-4V containing different levels of oxygen with temperature. Crossings of curves of the two phases are within the area of the rectangle which is enlarged in the inset at the bottom left corner, with the T0 temperatures of the crossings indicated. b Variations of the computed Tβ, T0 and Ms temperatures of Ti-Al-V with oxygen content

Fig. 4 XRD patterns of as-built Ti-6Al-4V containing different levels of oxygen, showing only α′ diffraction peaks

Fig. 5 SEM images showing microstructure change of SLMed Ti-6Al-4V with oxygen content on a XY plane, b YZ plane. The build direction is along OZ

Fig. 6 a Schematic illustration of the SLM process showing representative microtexyure maps of SLMed Ti-6Al-4V with β columnar grains (black dashed line) with respect to scan strategy YZ, and b contouring reconstructed orientation pole figures showing growth texture parallel to the build direction

Fig. 7 Microstructure of SLMed Ti–6Al–4V (0.25 wt% oxygen) showing a band contrast with CSL component defined $\left[ {11\overline{2}0} \right]$ intervariant misorientation of twin boundaries, neighboring random β phase. b Contouring component analysis of $\left\{ {10\overline{1}1} \right\}$ pole figure, c bright field image $,$ d dark field image of an α′ lath $,$ with selected area electron diffraction patterns of e the α′ phase and f the β phase.

Table 3 Martensite habit planes (hkl), its traces [uvw] on (001), and the angle (θ) between [uvw] and $\left[ {1\overline{1}0} \right]$ (the trace line of (334) habit plane), or between [uvw] and $\left[ {4\overline{3}0} \right]$ (the trace line of (344) habit plane)

(hkl)	[uvw]	θ (°)
$\left( {334} \right)$	$\left[ {1\overline{1}0} \right]$	-
$\left( {33\overline{4}} \right)$	$\left[ {1\overline{1}0} \right]$	0
$\left( {3\overline{3}4} \right)$	$\left[ {110} \right]$	90
$\left( {\overline{3}34} \right)$	$\left[ {110} \right]$	90
$\left( {433} \right)$	$\left[ {3\overline{4}0} \right]$	8.1
$\left( {43\overline{3}} \right)$	$\left[ {3\overline{4}0} \right]$	8.1
$\left( {4\overline{3}3} \right)$	$\left[ {340} \right]$	81.9
$\left( {\overline{4}33} \right)$	$\left[ {340} \right]$	81.9
$\left( {343} \right)$	$\left[ {4\overline{3}0} \right]$	8.1
$\left( {34\overline{3}} \right)$	$\left[ {4\overline{3}0} \right]$	8.1
$\left( {3\overline{4}3} \right)$	$\left[ {430} \right]$	81.9
$\left( {\overline{3}43} \right)$	$\left[ {430} \right]$	81.9
$\left( {344} \right)$	$\left[ {4\overline{3}0} \right]$	-
$\left( {34\overline{4}} \right)$	$\left[ {4\overline{3}0} \right]$	0
$\left( {3\overline{4}4} \right)$	$\left[ {430} \right]$	73.7
$\left( {\overline{3}44} \right)$	$\left[ {430} \right]$	73.7
$\left( {434} \right)$	$\left[ {3\overline{4}0} \right]$	16.3
$\left( {43\overline{4}} \right)$	$\left[ {3\overline{4}0} \right]$	16.3
$\left( {4\overline{3}4} \right)$	$\left[ {340} \right]$	90
$\left( {\overline{4}34} \right)$	$\left[ {340} \right]$	90
$\left( {443} \right)$	$\left[ {1\overline{1}0} \right]$	8.1
$\left( {44\overline{3}} \right)$	$\left[ {1\overline{1}0} \right]$	8.1
$\left( {4\overline{4}3} \right)$	$\left[ {110} \right]$	81.9
$\left( {\overline{4}43} \right)$	$\left[ {110} \right]$	81.9

Fig. 8 Four SEM images of Fig. 5a, with trace lines of martensite plates marked, and typical angles between these trace lines numbered from 1 to 12. A prior β grain boundary running down the middle of the second image is indicated by a dotted line

Table 4 Measured values of the angle number 1 to 12 marked on the SEM images of Fig. 8, together with the closest theoretical value of θ between traces of habit planes as listed in Table 3

Angle	Value (°)	θ (°)
1	7	8.1
2	13	16.3
3	90	90
4	70	73.7
5	90	90
6	75	73.7
7	70	73.7
8	68	73.7
9	9	8.1
10	70	73.7
11	72	73.7
12	73	73.7

Fig. 9 Average thickness (width) and length of the first generation of α′ martensite plates based on measurements on SEM images taken from a XY planes and b YZ planes

Table 5 Calculated growth restriction factors Q of different alloying additions in the investigated Ti-6Al-4V alloys

Alloy	Al	V	O
TC4-1	3.809	1.7556	2.09
TC4-2	3.8025	1.7556	3.04
TC4-3	3.8025	1.7472	3.990001
TC4-4	3.8675	1.7472	4.750001

Fig. 10 Analysis of intervariant crystallographic plane distribution of martensite in SLMed Ti-6Al-4V with different oxygen content: a inverse pole figure (IPF) maps, b contour plot of intervariant misorientation axis I, c contour plot of intervariant misorientation axes II + III, and d intensity distribution of specific disorientation angles associated with the Burgers orientation relationship for the alloy containing 0.25% oxygen, with the range of misorientation angle indicated

Fig. 11 a Inverse pole figure maps and b grain boundary misorientation of SLMed Ti-6Al-4V with different oxygen content

Fig. 12 a Schematic thermal cycle illustration showing b proposed phase transformation pathway of α′ martensite refinement during SLM processing of Ti-6Al-4V

References 83

[1]	R.R. Boyer, Mater. Sci. Eng. A 213, 103 (1996)
[2]	C. Cui, B. Hu, L. Zhao, S. Liu, Mater. Des. 32, 1684 (2011)
[3]	Y.L. Hao, S.J. Li, R. Yang, Rare Met. 35, 661 (2016)
[4]	I. Gurrappa, Mater. Charact. 51, 131 (2003)
[5]	G. Lütjering, J.C. Williams, Titanium, 2nd edn. (Springer, Berlin, 2007)
[6]	R. Huang, M. Riddle, D. Graziano, J. Warren, S. Das, S. Nimbalkar, J. Cresko, E. Masanet, J. Clean. Prod. 135, 1559 (2016)
[7]	S. Liu, Y.C. Shin, Mater. Des. 164, 107552 (2019)
[8]	D. Herzog, V. Seyda, E. Wycisk, C. Emmelmann, Acta Mater. 117, 371 (2016)
[9]	J. Yang, H. Yu, J. Yin, M. Gao, Z. Wang, X. Zeng, Mater. Des. 108, 308 (2016)
[10]	W. Xu, E.W. Lui, A. Pateras, M. Qian, M. Brandt, Acta Mater. 125, 390 (2017)
[11]	B. Van Hooreweder, D. Moens, R. Boonen, J.P. Kruth, P. Sas, Adv. Eng. Mater. 14, 92 (2012)
[12]	M. Simonelli, Y.Y. Tse, C. Tuck, Mater. Sci. Eng. A 616, 1 (2014)
[13]	B. Vrancken, L. Thijs, J.P. Kruth, J. Van Humbeeck, J. Alloys Compd. 541, 177 (2012)
[14]	W. Xu, M. Brandt, S. Sun, J. Elambasseril, Q. Liu, K. Latham, K. Xia, M. Qian, Acta Mater. 85, 74 (2015)
[15]	D. Ren, S. Li, H. Wang, W. Hou, Y. Hao, W. Jin, R. Yang, R.D.K. Misra, L.E. Murr, J. Mater. Sci. Technol. 35, 285 (2019)
[16]	N. Emminghaus, C. Hoff, J. Hermsdorf, S. Kaierle, Addit. Manuf. 46, 102093 (2021)
[17]	K. Dietrich, J. Diller, S. Dubiez-Le Goff, D. Bauer, P. Forêt, G. Witt, Addit. Manuf. 32, 100980 (2020)
[18]	H. Conrad, Prog. Mater. Sci. 26, 123 (1981)
[19]	A.I. Kahveci, G.E. Welsch, Scr. Metall. 20, 1287 (1986)
[20]	M. Yan, M.S. Dargusch, T. Ebel, M. Qian, Acta Mater. 68, 196 (2014)
[21]	G. Welsch, W. Bunk, Metall. Trans. A 13, 889 (1982)
[22]	R.R. Boyer, Titanium and Titanium Alloys, 9th edn. (American Society for Metals, 1985)
[23]	G. Hu, X. Cai, Y. Rong, Materials Science: Volume 1 Structure (De Gruyter,
[24]	T.S. Prithiv, Z. Kloenne, D. Li, R. Shi, Y. Zheng, H.L. Fraser, B. Gault, S. Antonov, Scr. Mater. 207, 114320 (2022)
[25]	C. Katinas, S. Liu, Y.C. Shin, J. Manuf. Sci. Eng. 141, 011001 (2018)
[26]	S. Liu, Y.C. Shin, Mater. Des. 159, 212 (2018)
[27]	Y. Zhu, K. Zhang, Z. Meng, K. Zhang, P. Hodgson, N. Birbilis, M. Weyland, H.L. Fraser, S.C.V. Lim, H. Peng, R. Yang, H. Wang, A. Huang, Nat. Mater. 21, 1258 (2022)
[28]	H.K. Rafi, N.V. Karthik, H. Gong, T.L. Starr, B.E. Stucker, J. Mater. Eng. Perform. 22, 3872 (2013)
[29]	N. Kazantseva, P. Krakhmalev, M. Thuvander, I. Yadroitsev, N. Vinogradova, I. Ezhov, Mater. Charact. 146, 101 (2018)
[30]	J. He, D. Li, W. Jiang, L. Ke, G. Qin, Y. Ye, Q. Qin, D. Qiu, Materials (Basel). 12, 321 (2019)
[31]	L. Thijs, F. Verhaeghe, T. Craeghs, J. Van Humbeeck, J.P. Kruth, Acta Mater. 58, 3303 (2010)
[32]	T. Ahmed, H.J. Rack, Mater. Sci. Eng. A 243, 206 (1998)
[33]	S.M. Kelly, S.L. Kampe, Metall. Mater. Trans. A 35, 1869 ( 2004)
[34]	A. Crespo, R. Vilar, Scr. Mater. 63, 140 (2010)
[35]	J. Ahn, E. He, L. Chen, R.C. Wimpory, J.P. Dear, C.M. Davies, Mater. Des. 115, 441 (2017)
[36]	C. Kenel, D. Grolimund, X. Li, E. Panepucci, V.A. Samson, D.F. Sanchez, F. Marone, C. Leinenbach, Sci. Rep. 7, 16358 (2017) DOI PMID
[37]	H.S. Tran, J.T. Tchuindjang, H. Paydas, A. Mertens, R.T. Jardin, L. Duchêne, R. Carrus, J. Lecomte-Beckers, A.M. Habraken, Mater. Des. 128, 130 (2017)
[38]	S. Neelakantan, P.E.J. Rivera-Díaz-del-Castillo, S. van der Zwaag, Scr. Mater. 60, 611 (2009)
[39]	Y. Kuang,Thesis: Generation of TTT and CCT Curves for Cast Ti-6Al-4V Alloy, Univeristy of Florida, 2004.
[40]	J.T. Tchuindjang, H. Paydas, H.S. Tran, R. Carrus, L. Duchêne, A. Mertens, A.M. Habraken, Mater. 14, 2985 (2021)
[41]	E.I. Galindo-Nava, Scr. Mater. 138, 6 (2017)
[42]	M. Klinger, J. Appl. Crystallogr. 50, 1226 (2017)
[43]	J. Tiley, T. Searles, E. Lee, S. Kar, R. Banerjee, J.C. Russ, H.L. Fraser, Mater. Sci. Eng. A 372, 191 (2004)
[44]	P.C. Collins, B. Welk, T. Searles, J. Tiley, J.C. Russ, H.L. Fraser, Mater. Sci. Eng. A 508, 174 (2009)
[45]	B.J. Hayes, B.W. Martin, B. Welk, S.J. Kuhr, T.K. Ales, D.A. Brice, I. Ghamarian, A.H. Baker, C.V. Haden, D.G. Harlow, H.L. Fraser, P.C. Collins, Acta Mater. 133, 120 (2017)
[46]	S.L. Chen, S. Daniel, F. Zhang, Y.A. Chang, X.Y. Yan, F.Y. Xie, R. Schmid-Fetzer, W.A. Oates,Calphad 26, 175 (2002)
[47]	L.E. Tanner, Time-Temperature-Transformation Diagrams of the Titanium Sheet-Rolling-Program Alloys (Report on Department of Defense, United States,
[48]	G. Welsch, R. Boyer, E.W. Collings, Materials Properties Handbook: Titanium Alloys (ASM International,
[49]	M. Majdic, G. Ziegler, Met. Res. Adv. Technol. 64, 751 (1973)
[50]	G. Ghosh, G.B. Olson, Acta Metall. Mater. 42, 3361 (1994)
[51]	G. Ghosh, G.B. Olson, Acta Metall. Mater. 42, 3371 (1994)
[52]	Y.C. Huang, S. Suzuki, H. Kaneko, T. Sato, in Science, Technology and Application of Titanium, ed. by R. I. Jaffee and Promisel (Pergamon, 1970), pp. 691-693
[53]	L. Kaufman, Acta Metall. 7, 575 (1959)
[54]	S. Banerjee, P. Mukhopadhyay, Phase Transformations: Examples from Titanium and Zirconium Alloys, 1st edn. (Pergamon Materials Series, Elsevier, Oxford, 2007)
[55]	H.H. Weigand, Int. J. Mater. Res. 54, 43 (1963)
[56]	S.S. Al-Bermani, M.L. Blackmore, W. Zhang, I. Todd, Metall. Mater. Trans. A 41, 3422 (2010)
[57]	E. Farabi, V. Tari, P.D. Hodgson, G.S. Rohrer, H. Beladi, J. Mater. Sci. 55, 15299 (2020)
[58]	A. Kelly, K.M. Knowles, Crystallography and Crystal Defects, 3rd edn. (Wiley, 2012)
[59]	K.M. Knowles, D.A. Smith, Acta Metall. 29, 1445 (1981)
[60]	Y.C. Liu,JOM 8, 1036 (1956)
[61]	Y.C. Liu, H. Margolin,JOM 5, 667 (1953)
[62]	C. Hammond, P.M. Kelly, Acta Metall. 17, 869 (1969)
[63]	T. Nyyssönen, A.A. Gazder, R. Hielscher, F. Niessen, Acta Mater. 255, 119035 (2023)
[64]	G.M. Ter Haar, T.H. Becker, Mater. Sci. Eng. A 814, 141185 (2021)
[65]	J.K. Mackenzie, J.S. Bowles, Acta Metall. 5, 137 (1957)
[66]	S. Banerjee, R. Krishnan, Metall. Trans. 4, 1811 ( 1973)
[67]	E. Farabi, P.D. Hodgson, G.S. Rohrer, H. Beladi, Acta Mater. 154, 147 (2018)
[68]	H. Matsumoto, H. Yoneda, K. Sato, S. Kurosu, E. Maire, D. Fabregue, T.J. Konno, A. Chiba, Mater. Sci. Eng. A 528, 1512 (2011)
[69]	M.V. Pantawane, S. Sharma, A. Sharma, S. Dasari, S. Banerjee, R. Banerjee, N.B. Dahotre, Acta Mater. 213, 116954 (2021)
[70]	Z. Yang, F. Wen, Q. Sun, L. Chai, X. Ma, M. Zhu. (SSRN Electronic Journal, 2022), https://ssrn.com/abstract=4134176. Accessed 7 Oct 2022
[71]	M.J. Bermingham, S.D. McDonald, M.S. Dargusch, D.H. StJohn, J. Mater. Res. 23, 97 (2008)
[72]	M. Simonelli, D.G. McCartney, P. Barriobero-Vila, N.T. Aboulkhair, Y.Y. Tse, A. Clare, R. Hague, Metall. Mater. Trans. A 51, 2444 (2020)
[73]	M. Tahara, T. Inamura, H.Y. Kim, S. Miyazaki, H. Hosoda, Scr. Mater. 112, 15 (2016)
[74]	Q. Liang, D. Wang, Y. Zheng, S. Zhao, Y. Gao, Y. Hao, R. Yang, D. Banerjee, H.L. Fraser, Y. Wang, Acta Mater. 186, 415 (2020)
[75]	M. Tahara, H.Y. Kim, T. Inamura, H. Hosoda, S. Miyazaki, Acta Mater. 59, 6208 (2011)
[76]	H. Beladi, Q. Chao, G.S. Rohrer, Acta Mater. 80, 478 (2014)
[77]	S.C. Wang, M. Aindow, M.J. Starink, Acta Mater. 51, 2485 (2003)
[78]	D. Bhattacharyya, G.B. Viswanathan, R. Denkenberger, D. Furrer, H.L. Fraser, Acta Mater. 51, 4679 (2003)
[79]	R. Shi, V. Dixit, H.L. Fraser, Y. Wang, Acta Mater. 75, 156 (2014)
[80]	Y. Zheng, R.E.A. Williams, S. Nag, R. Banerjee, H.L. Fraser, D. Banerjee, Scr. Mater. 116, 49 (2016)
[81]	S. Lee, C. Park, J. Hong, J.T. Yeom, Sci. Rep. 8, 11914 (2018)
[82]	Z. Nishiyama, M. Oka, Mater. Trans. Japan Inst. Met. Mater. 7, 174 (1966)
[83]	H. Wang, Q. Chao, L. Yang, M. Cabral, Z.Z. Song, B.Y. Wang, S. Primig, W. Xu, Z.B. Chen, S.P. Ringer, X.Z. Liao, Mater. Res. Lett. 9, 119 (2021)