-
This document is downloaded from DR‑NTU (https://dr.ntu.edu.sg)Nanyang Technological University, Singapore.
Selective electron beam melting of Co‑Cr‑Mo :microstructure and mechanical properties
Tan, Xipeng; Wang, Pan; Nai, Sharon; Liu, Erjia; Tor, Shu Beng
2018
Tan, X., Wang, P., Nai, S., Liu, E., & Tor, S. B. (2018). Selective electron beam melting ofCo‑Cr‑Mo : microstructure and mechanical properties. Proceedings of the 3rd InternationalConference on Progress in Additive Manufacturing (Pro‑AM 2018), 535‑540.doi:10.25341/D4201S
https://hdl.handle.net/10356/88877
https://doi.org/10.25341/D4201S
© 2018 Nanyang Technological University. Published by Nanyang Technological University,Singapore.
Downloaded on 07 Apr 2021 03:08:12 SGT
-
ABSTRACT: As an emerging powder-bed fusion additive
manufacturing technique, selective electron beam melting (SEBM)
attracts numerous attentions due to its great potential
applications in orthopaedic implants and aerospace components. The
microstructure and mechanical properties of SEBM-built Co-Cr-Mo
alloy have been investigated. Microstructural characterisation was
carried out using scanning electron microscopy, and X-ray
diffraction techniques. Its microstructure consists of face-centred
cubic columnar grains with preferred orientation and continuous
carbide thin films at grain boundaries. Each columnar grain is
comprised of parallel dendrites with short secondary arms and
sparse carbides within interdendritic regions. Two sorts of
carbides were identified in terms of their compositions, i.e. C23M6
and C6M (where M = Co, Cr and Mo). In addition, anisotropic
mechanical properties were found to exist in SEBM-built Co-Cr-Mo
parts. The microstructure-property relationship for SEBM-built
Co-Cr-Mo parts is discussed. KEYWORDS: additive manufacturing, EBM,
Co-Cr-Mo alloy, microstructure, mechanical properties
INTRODUCTION
Selective electron beam melting (SEBM) is a promising powder-bed
fusion additive manufacturing (AM) technology for metals and
alloys, and it is being increasingly used in producing complex
orthopeadic implants and aerospace components (Tan et al. 2014; Kok
et al. 2015). In addition to some process-induced defects, such as
internal pores and rough surface, another critical issue that may
obstacle its wide applications is the limited material library for
SEBM process. Ti-6Al-4V is still the most investigated material in
SEBM and its microstructure and mechanical properties have been
extensively reported [Wang et al. 2016; Tan et al. 2015; Tan et al.
2016]. However, only limited studies were involved in SEBM
processing of Co-Cr-Mo alloys [Kircher et al. 2009; Gaytan et al.
2010; Sun et al. 2014; Sun et al. 2015; Kok et al. 2018; Tan et al.
2018]. Co-Cr-Mo alloys are widely used in both biomedical and
aerospace applications where require good biocompatibility, high
wear resistence, and superior high-temperature creep properties
[Davis 2000].
In recent years, microstructural consistency, i.e. anisotropy
and homogeneity of microstructure, has become another important
concern when seeking practical applications of SEBM as well as
other metal AM techniques. Sun et al. [Sun et al. 2014] reported
the build direction and build height dependent microstructure and
their effects on high-temperature tensile and creep properties for
SEBM-built Co-Cr-Mo. Kircher et al. [Kircher et al. 2009] suggested
that as-SEBM-built Co-Cr-Mo has significantly better mechanical
properties as compared to its wrought and as-cast forms. The
SEBM-built Co-Cr-Mo, however, was found to be more brittle with a
markedly lower elongation before failure. This is especially so
when the load was applied normal to the z-direction
SELECTIVE ELECTRON BEAM MELTING OF CO-CR-MO: MICROSTRUCTURE AND
MECHANICAL PROPERTIES
XIPENG TAN1, PAN WANG2, SHARON NAI2, ERJIA LIU1, SHU BENG TOR1
1Singapore Centre for 3D Printing, School of Mechanical and
Aerospace Engineering, Nanyang
Technological University, 50 Nanyang Avenue, Singapore 639798 2
Singapore Institute of Manufacturing Technology, 73 Nanyang Drive,
Singapore 637662
535
Proc. Of the 3rd Intl. Conf. on Progress in Additive
Manufacturing (Pro-AM 2018) Edited by Chee Kai Chua, Wai Yee Yeong,
Ming Jen Tan, Erjia Liu and Shu Beng TorCopyright © 2018 by Nanyang
Technological UniversityPublished by Nanyang Technological
University ISSN: 2424-8967 :: https://doi.org/10.25341/D4201S
-
Chee Kai Chua, Wai Yee Yeong, Ming Jen Tan, Erjia Liu and Shu
Beng Tor (Eds.)
536
-
Proc. Of the 3rd Intl. Conf. on Progress in Additive
Manufacturing
537
-
Chee Kai Chua, Wai Yee Yeong, Ming Jen Tan, Erjia Liu and Shu
Beng Tor (Eds.)
538
-
Proc. Of the 3rd Intl. Conf. on Progress in Additive
Manufacturing
539
-
Kok, Y., Tan, X.P., Tor, S.B., & Chua, C.K. (2015).
Fabrication and microstructural characterisation of additive
manufactured Ti-6Al-4V parts by electron beam melting. Virtual and
Physical Prototyping, 10(1), 13-21.
Wang, P., et al. (2016). Recent progress of additive
manufactured Ti-6Al-4V by electron beam melting. In Proceedings of
the 2016 Annual International Solid Freeform Fabrication Symposium
(SFF Symp 2016), Austin: Univ. Tex., 691-704.
Tan, X.P., et al. (2015). Graded microstructure and mechanical
properties of additive manufactured Ti–6Al–4V via electron beam
melting. Acta Materialia, 97, 1-16.
Tan, X.P., et al. (2016). Revealing martensitic transformation
and / interface evolution in electron beam melting
three-dimensional-printed Ti-6Al-4V. Scientific Reports, 6,
26039.
Kircher, R. S., Christensen, A. M., & Wurth, K. W. (2009).
Electron beam melted (EBM) Co-Cr-Mo alloy for orthopaedic implant
applications. In Solid Freeform Fabrication Proceedings. Austin:
Univ. Tex. 428-436.
Gaytan, S. M., et al. (2010). Comparison of microstructures and
mechanical properties for solid and mesh cobalt-base alloy
prototypes fabricated by electron beam melting. Metallurgical and
Materials Transactions A, 41(12), 3216-3227.
Sun, S. H., Koizumi, Y., Kurosu, S., Li, Y. P., Matsumoto, H.,
& Chiba, A. (2014). Build direction dependence of
microstructure and high-temperature tensile property of Co–Cr–Mo
alloy fabricated by electron beam melting. Acta Materialia, 64,
154-168.
Sun, S. H., Koizumi, Y., Kurosu, S., Li, Y. P., & Chiba, A.
(2015). Phase and grain size inhomogeneity and their influences on
creep behavior of Co–Cr–Mo alloy additive manufactured by electron
beam melting. Acta Materialia, 86, 305-318.
Kok, Y., et al. (2018). Anisotropy and heterogeneity of
microstructure and mechanical properties in metal additive
manufacturing: A critical review. Materials & Design, 139,
565-586.
Tan, X. P., et al. (2018). Carbide precipitation characteristics
in additive manufacturing of Co-Cr-Mo alloy via selective election
beam melting. Scripta Materialia, 143, 117-121.
Davis, J. R. (Ed.). (2000). Nickel, cobalt, and their alloys.
ASM international.
Chee Kai Chua, Wai Yee Yeong, Ming Jen Tan, Erjia Liu and Shu
Beng Tor (Eds.)
540