Influence of Layer Thickness on Microstructure and Mechanical Properties of Selective Laser Melted Ti-5Al-2.5Sn Alloy

doi:10.11900/0412.1961.2017.00384

Acta Metall Sin

2018, Vol. 54

Issue (7): 999-1009 DOI: 10.11900/0412.1961.2017.00384

Current Issue | Archive | Adv Search

Influence of Layer Thickness on Microstructure and Mechanical Properties of Selective Laser Melted Ti-5Al-2.5Sn Alloy

Piao GAO, Kaiwen WEI, Hanchen YU, Jingjing YANG, Zemin WANG(

), Xiaoyan ZENG

Wuhan National Laboratory for Optoelectronics, Huazhong University of Science and Technology, Wuhan 430074, China

Cite this article:

Piao GAO, Kaiwen WEI, Hanchen YU, Jingjing YANG, Zemin WANG, Xiaoyan ZENG. Influence of Layer Thickness on Microstructure and Mechanical Properties of Selective Laser Melted Ti-5Al-2.5Sn Alloy. Acta Metall Sin, 2018, 54(7): 999-1009.

Download:

HTML

PDF(6969KB)
Export: BibTeX | EndNote (RIS)

Abstract

As an additive manufacturing technology, selective laser melting (SLM) process can solve the manufacturing difficulty of Ti-5Al-2.5Sn (TA7) easily. But the low building efficiency of SLM retards its wide applications in aviation, petrochemical and other fields. In order to solve the above problem, the influence of layer thickness on relative density, microstructure and mechanical properties of SLMed TA7 samples were studied in this work. The results show that when the laser power and hatching space are constant, the relative density gradually increases with the decrease of the laser volume energy density under the layer thicknesses less than or equal to 40 μm, whereas first increases and then declines with the decrease of the laser volume energy density under the layer thicknesses larger than 40 μm. At the same time, with the increase of layer thickness and the decrease of scanning velocity, the cooling rate gradually decreases during the SLM processing, when the cooling rate is lower than 6.8×10⁷ K/s, the microstructure will gradually transform from acicular martensite α' to massive α_m. Through the optimization of SLM parameters, the dense TA7 bulk specimens with higher microhardnesses, yield strengths and ultimate strengths in comparison to the as-cast and deformed TA7 alloys can be obtained under all layer thicknesses (20~60 μm). While when the layer thicknesses are not larger than 40 μm, the ductility of the SLMed TA7 is also superior to that of the as-cast TA7 and comparable to that of the deformed TA7. Finally, the optimal layer thickness and combination of SLM process parameters are successfully determined to balance the building efficiency, metallurgical quality and mechanical properties of the TA7 alloy parts.

Key words: selective laser melting layer thickness Ti-5Al-2.5Sn alloy microstructure mechanical property

Received: 13 September 2017

ZTFLH:

TN249

Fund: Supported by National Basic Research Program of China (No.613281), Fundamental Research Funds for the Central Universities (No.2016XYZD005) and Technical Basis Project of State Administration of Science and Technology and Industry for National Defense (No.JSCG2016204B001)

	Service

	E-mail this article
	Add to citation manager
	E-mail Alert
	RSS
	（）
	Articles by authors
	Piao GAO
	Kaiwen WEI
	Hanchen YU
	Jingjing YANG
	Zemin WANG
	Xiaoyan ZENG

URL:

https://www.ams.org.cn/EN/10.11900/0412.1961.2017.00384 OR https://www.ams.org.cn/EN/Y2018/V54/I7/999

Table 1 Parameters for selective laser melting process

Fig.1 SEM image (a) and particle size distribution (b) of TA7 alloy powders (D10, D50 and D90 are the diameters at which 10%, 50% and 90% of the samples' mass are comprised of particles with a diameter less than these values)

Fig.2 The variation of the relative density and volume energy density with the process parameters under layer thicknesses δ=20 μm (a), δ=30 μm (b), δ=40 μm (c), δ=50 μm (d) and δ=60 μm (e) (Insets a1 shows the molten pool morphology of a single track, the dotted line represents the boundary of the molten pool, the pore in the molten pool shows the 'keyhole effect'; insets a2, b1, c1, d1 and e1 show the circular pores in the samples; insets c2, d2 and e2 show the irregularly unmelted voids in the samples)

Table 2 The relative density and process parameters of the densest TA7 samples under different layer thicknesses

Fig.3 OM image (a) and SEM image (b) of the acicular α′ martensites and EDS analysis of the position P in Fig.3b (c) (δ=20 μm, V=1000 mm/s, S=0.08 mm)

Fig.4 OM image (a) and SEM image (b) of the acicular α′+massive α_m microstructures and EDS analyses of the position P1 (c) and position P2 (d) in Fig.4b (δ=40 μm, V=600 mm/s, S=0.08 mm)

Fig.5 OM image (a) and SEM image (b) of the massive α_m microstructures and EDS analysis of the position P in Fig.5b (c) (δ=60 μm, V=400 mm/s, S=0.08 mm)

Fig.6 XRD spectra of the TA7 bulk samples corresponding to three types of microstructures respectively

Fig.7 Relationship between metallographic structures of TA7 samples and process parameters (P=200 W, S=0.06 mm, 0.08 mm and 0.10 mm)

Fig.8 The variation of diameters of the molten pools with the layer thickness and scanning velocity

Fig.9 The variation of cooling rates of the molten pools with the layer thickness and scanning velocity

Fig.10 Microstructures of the densest TA7 samples under layer thicknesses δ=20 μm (a), δ=30 μm (b), δ=40 μm (c), δ=50 μm (d) and δ=60 μm (e) (ΔT—variation of temperature, Δt—variation of time, ΔT/Δt—cooling rate of the molten pool)

Fig.11 Trends of microhardnesses and tensile properties with layer thickness for the five densest TA7 samples

Table 3 Mechanical properties of the conventional deformed and as-cast TA7 alloy^[20,30,31]

Fig.12 SEM images of tensile fracture morphologies of the densest TA7 tensile samples deposited by layer thicknesses of δ=20 μm (a), δ=30 μm (b), δ=40 μm (c), δ=50 μm (d) and δ=60 μm (e)

[1]	Li Y K, Quan C Y, Lu S P, et al.Study on shape correction of the thin plate of TA15 titanium alloy by post weld heat treatment[J]. Acta Metall. Sin., 2016, 52: 281(李永奎, 权纯逸, 陆善平等. TA15钛合金薄壁焊接件热处理校形研究[J]. 金属学报, 2016, 52: 281)
[2]	Zhang X Y, Zhao Y Q, Bai C G.Titanium Alloys and Applications [M]. Beijing: Chemical Industry Press, 2004: 82(张喜燕, 赵永庆, 白晨光. 钛合金及应用 [M]. 北京: 化学工业出版社, 2004: 82)
[3]	Donachie M J.Titanium: A Technical Guide[M]. 2nd Ed., Materials Park, OH: ASM International, 2000: 11
[4]	Huang W P, Yu H C, Yin J, et al.Microstructure and mechanical properties of K4202 cast nickel base superalloy fabricated by selective laser melting[J]. Acta Metall. Sin., 2016, 52: 1089(黄文普, 喻寒琛, 殷杰等. 激光选区熔化成形K4202镍基铸造高温合金的组织和性能[J]. 金属学报, 2016, 52: 1089)
[5]	Zhang W Q, Zhu H H, Hu Z H, et al.Study on the selective laser melting of AlSi10Mg[J]. Acta Metall. Sin., 2017, 53: 918(张文奇, 朱海红, 胡志恒等. AlSi10Mg的激光选区熔化成形研究[J]. 金属学报, 2017: 53: 918)
[6]	Wang Z M, Guan K, Gao M, et al.The microstructure and mechanical properties of deposited-IN718 by selective laser melting[J]. J. Alloys Compd., 2012, 513: 518
[7]	Ma M M, Wang Z M, Wang D Z, et al.Control of shape and performance for direct laser fabrication of precision large-scale metal parts with 316L stainless steel[J]. Opt. Laser. Technol., 2013, 45: 209
[8]	Yu H C, Yang J J, Yin J, et al.Comparison on mechanical anisotropies of selective laser melted Ti-6Al-4V alloy and 304 stainless steel[J]. Mater. Sci. Eng., 2017, A695: 92
[9]	Yablokova G, Speirs M, Van Humbeeck J, et al.Rheological behavior of β-Ti and NiTi powders produced by atomization for SLM production of open porous orthopedic implants[J]. Powder Technol., 2015, 283: 199
[10]	Zhou Y, Wen S F, Song B, et al.A novel titanium alloy manufactured by selective laser melting: Microstructure, high temperature oxidation resistance[J]. Mater. Des., 2016, 89: 1199
[11]	Wei K W, Wang Z M, Zeng X Y.Preliminary investigation on selective laser melting of Ti-5Al-2.5Sn α-Ti alloy: From single tracks to bulk 3D components[J]. J. Mater. Process. Technol., 2017, 244: 73
[12]	Ma M M, Wang Z M, Zeng X Y, et al.Layer thickness dependence of performance in high-power selective laser melting of 1Cr18Ni9Ti stainless steel[J]. J. Mater. Process. Technol., 2015, 215: 142
[13]	Choi J, Chang Y.Characteristics of laser aided direct metal/material deposition process for tool steel[J]. Int. J. Mach. Tool. Man., 2005, 45: 597
[14]	Shim D S, Baek G Y, Seo J S, et al.Effect of layer thickness setting on deposition characteristics in direct energy deposition (DED) process[J]. Opt. Laser. Technol., 2016, 86: 69
[15]	Panda B N, Garg A, Shankhwar K.Empirical investigation of environmental characteristic of 3-D additive manufacturing process based on slice thickness and part orientation[J]. Measurement, 2016, 86: 293
[16]	Aboulkhair N T, Maskery I, Tuck C, et al.On the formation of AlSi10Mg single track and layers in selective laser melting: Microstructure and nano-mechanical properties[J]. J. Mater. Process. Technol., 2016, 230: 88
[17]	Chen G X, Zeng X Y.Design and development of equipment of selective laser melting rapid prototyping[J]. Mech. Design. Manuf., 2010, (8): 15(陈光霞, 曾晓雁. SLM激光快速成型设备的设计与开发[J]. 机械设计与制造, 2010, (8): 15)
[18]	Chen G X, Zeng X Y.Design on SLM powder coating device[J]. Manuf. Technol. Mach. Tool, 2012, (3): 57(陈光霞, 曾晓雁. 选择性激光熔化激光快速成型铺粉装置设计[J]. 设计与研究, 2012, (3): 57)
[19]	Zou W Z, Guo X G, Xie X Y, et al.Titanium Handbook [M]. Beijing: Chemical Industry Press, 2012: 338
[20]	Wei K W, Wang Z M, Zeng X Y.Element loss of AZ91D magnesium alloy during selective laser melting process[J]. Acta Metall. Sin., 2016, 52: 184(魏恺文, 王泽敏, 曾晓雁. AZ91D镁合金在激光选区熔化成形中的元素烧损[J]. 金属学报, 2016, 52: 184)
[21]	Krutha J P, Froyen L, Vaerenbergh J V, et al.Selective laser melting of iron-based powder[J]. J. Mater. Process. Technol., 2004, 149: 616
[22]	King W E, Barth H D, Castillo V M, et al.Observation of keyhole-mode laser melting in laser powder-bed fusion additive manufacturing[J]. J. Mater. Process. Technol., 2014, 214: 2915
[23]	Kamath C, El-Dasher B, Gallegos G F, et al.Density of additively-manufactured, 316LSS parts using laser powder-bed fusion at powers up to 400 W[J]. Int. J. Adv. Manuf. Technol., 2014, 74: 65
[24]	Collings E W, Welsch G.Materials Properties Handbook: Titanium Alloys[M]. Materials Park, OH: ASM International, 1994: 289
[25]	Alphons A A.Microstructure, texture and mechanical property evolution during additive manufacturing of Ti6Al4V alloy for aerospace applications [D]. Manchester, UK: The University of Manchester, 2012: 61
[26]	Ahmed T, Rack H J.Phase transformations during cooling in α+β titanium alloys[J]. Mater. Sci. Eng., 1998, A243: 206
[27]	Hofmeister W, Griffith M.Solidification in direct metal deposition by LENS processing[J]. JOM., 2001, 53(9): 30
[28]	Zhang B C, Liao H L, Christian C.Microstructure evolution and density behavior of CP-Ti parts elaborated by self-developed vacuum selective laser melting system[J]. Appl. Surf. Sci., 2013, 279: 310
[29]	Gu D D, Christian Y H, Wilhelm M, et al.Densification behavior, microstructure evolution, and wear performance of selective laser melting processed commercially pure titanium[J]. Acta Mater., 2012, 60: 3849
[30]	Yan W Q, Dai L, Gui C B.In situ synthesis and hardness of TiC/Ti5Si3 composites on Ti-5A1-2.5Sn substrates by gas tungsten arc welding[J]. Int. J. Min. Met. Mater., 2013, 20: 284
[31]	Boonruang C, Thong-on A. Tribological behavior of Ti-5Al-2.5Sn: Ti-10V-2Fe-3Al and Ti-38Al carburized via current heating technique withgraphite powders[J]. Mater. Trans., 2014, 55: 1073
[32]	Shi K, Xie H S, Zhao J, et al.Influence of vacuum annealing on microstructure and properties of cast Ti-5Al-2.5Sn eli alloy welding sample[J]. Foundry., 2015, 64: 202(史昆, 谢华生, 赵军等. 真空退火对铸造Ti-5Al-2.5SnELI合金焊接试样组织与性能的影响[J]. 铸造, 2015, 64: 202)

[1]	ZHENG Liang, ZHANG Qiang, LI Zhou, ZHANG Guoqing. Effects of Oxygen Increasing/Decreasing Processes on Surface Characteristics of Superalloy Powders and Properties of Their Bulk Alloy Counterparts: Powders Storage and Degassing[J]. 金属学报, 2023, 59(9): 1265-1278.
[2]	ZHANG Leilei, CHEN Jingyang, TANG Xin, XIAO Chengbo, ZHANG Mingjun, YANG Qing. Evolution of Microstructures and Mechanical Properties of K439B Superalloy During Long-Term Aging at 800^oC[J]. 金属学报, 2023, 59(9): 1253-1264.
[3]	LU Nannan, GUO Yimo, YANG Shulin, LIANG Jingjing, ZHOU Yizhou, SUN Xiaofeng, LI Jinguo. Formation Mechanisms of Hot Cracks in Laser Additive Repairing Single Crystal Superalloys[J]. 金属学报, 2023, 59(9): 1243-1252.
[4]	GONG Shengkai, LIU Yuan, GENG Lilun, RU Yi, ZHAO Wenyue, PEI Yanling, LI Shusuo. Advances in the Regulation and Interfacial Behavior of Coatings/Superalloys[J]. 金属学报, 2023, 59(9): 1097-1108.
[5]	ZHANG Jian, WANG Li, XIE Guang, WANG Dong, SHEN Jian, LU Yuzhang, HUANG Yaqi, LI Yawei. Recent Progress in Research and Development of Nickel-Based Single Crystal Superalloys[J]. 金属学报, 2023, 59(9): 1109-1124.
[6]	WANG Lei, LIU Mengya, LIU Yang, SONG Xiu, MENG Fanqiang. Research Progress on Surface Impact Strengthening Mechanisms and Application of Nickel-Based Superalloys[J]. 金属学报, 2023, 59(9): 1173-1189.
[7]	LIU Xingjun, WEI Zhenbang, LU Yong, HAN Jiajia, SHI Rongpei, WANG Cuiping. Progress on the Diffusion Kinetics of Novel Co-based and Nb-Si-based Superalloys[J]. 金属学报, 2023, 59(8): 969-985.
[8]	DING Hua, ZHANG Yu, CAI Minghui, TANG Zhengyou. Research Progress and Prospects of Austenite-Based Fe-Mn-Al-C Lightweight Steels[J]. 金属学报, 2023, 59(8): 1027-1041.
[9]	LI Jingren, XIE Dongsheng, ZHANG Dongdong, XIE Hongbo, PAN Hucheng, REN Yuping, QIN Gaowu. Microstructure Evolution Mechanism of New Low-Alloyed High-Strength Mg-0.2Ce-0.2Ca Alloy During Extrusion[J]. 金属学报, 2023, 59(8): 1087-1096.
[10]	CHEN Liqing, LI Xing, ZHAO Yang, WANG Shuai, FENG Yang. Overview of Research and Development of High-Manganese Damping Steel with Integrated Structure and Function[J]. 金属学报, 2023, 59(8): 1015-1026.
[11]	SUN Rongrong, YAO Meiyi, WANG Haoyu, ZHANG Wenhuai, HU Lijuan, QIU Yunlong, LIN Xiaodong, XIE Yaoping, YANG Jian, DONG Jianxin, CHENG Guoguang. High-Temperature Steam Oxidation Behavior of Fe22Cr5Al3Mo-xY Alloy Under Simulated LOCA Condition[J]. 金属学报, 2023, 59(7): 915-925.
[12]	YUAN Jianghuai, WANG Zhenyu, MA Guanshui, ZHOU Guangxue, CHENG Xiaoying, WANG Aiying. Effect of Phase-Structure Evolution on Mechanical Properties of Cr₂AlC Coating[J]. 金属学报, 2023, 59(7): 961-968.
[13]	WANG Fa, JIANG He, DONG Jianxin. Evolution Behavior of Complex Precipitation Phases in Highly Alloyed GH4151 Superalloy[J]. 金属学报, 2023, 59(6): 787-796.
[14]	ZHANG Deyin, HAO Xu, JIA Baorui, WU Haoyang, QIN Mingli, QU Xuanhui. Effects of Y₂O₃ Content on Properties of Fe-Y₂O₃ Nanocomposite Powders Synthesized by a Combustion-Based Route[J]. 金属学报, 2023, 59(6): 757-766.
[15]	WU Dongjiang, LIU Dehua, ZHANG Ziao, ZHANG Yilun, NIU Fangyong, MA Guangyi. Microstructure and Mechanical Properties of 2024 Aluminum Alloy Prepared by Wire Arc Additive Manufacturing[J]. 金属学报, 2023, 59(6): 767-776.

No Suggested Reading articles found!

Viewed

Full text

Abstract

Cited

Shared

Discussed