Citation: Li, J.; Yang, Y.; Zhu, G.;
Sun, C.; Chen, Y.; Wang, K.; Shi, S.
The Anisotropic Electrochemical
Machinability of Laser Cladding
Deposited Ti6Al4V Alloy in NaCl
Solution. Materials 2022, 15, 3642.
https://doi.org/10.3390/ma15103642
Academic Editors: Ludwig Cardon
and Clemens Holzer
Received: 26 April 2022
Accepted: 18 May 2022
Published: 19 May 2022
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Article
The Anisotropic Electrochemical Machinability of Laser
Cladding Deposited Ti6Al4V Alloy in NaCl Solution
Jiaqiang Li
1,2
, Yuan Yang
3
, Gangxian Zhu
1
, Chengfeng Sun
1
, Yiyang Chen
1,
* , Kejun Wang
1,
*
and Shihong Shi
1
1
School of Mechanical and Electric Engineering, Soochow University, Suzhou 215021, China;
lijq@suda.edu.cn (J.L.); gxzhu@suda.edu.cn (G.Z.); sunchengfeng@suda.edu.cn (C.S.); ljq.yy@163.com (S.S.)
2
Advanced Manufacturing Technology Research Center, Department of Industrial and Systems Engineering,
The Hong Kong Polytechnic University, Kowloon, Hong Kong
3
Suzhou Electromachining Machine Tool Research Institute Co., Ltd., Suzhou 215011, China;
klyangyuan@163.com
* Correspondence: yychen90@suda.edu.cn (Y.C.); kjwang@suda.edu.cn (K.W.)
Abstract:
The hybrid manufacturing method of laser cladding deposition (LCD) additive manufac-
turing and electrochemical machining (ECM) is a promising approach to advanced manufacturing
technology for difficult machined materials. The anisotropic electrochemical performance of LCD-
produced Ti6Al4V alloy was studied in 15 wt.% NaCl solution by polarization curve measurements
and ECM tests. The horizontal-plane (X0Y plane) exhibits a more stable passive film in both static
electrolyte and low current density ECM processes than the vertical-plane (X0Z plane). Addition-
ally, the horizontal-plane exhibits a higher material removal rate and more consistent dissolved
surface roughness in comparison with the vertical-plane during the high current density ECM pro-
cess. The microstructure of the LCD-produced Ti6Al4V alloy on the horizontal-plane consisted of
equiaxed-like prior-
β
grains and slightly finer
α
-laths but was composed by columnar prior-
β
grains
and coarser
α
-laths on the vertical-plane. These differences in the microstructural characteristics
produce the distinctions observed in the electrochemical dissolution behavior and electrochemical
machinability on the horizontal- and vertical-planes.
Keywords:
additive manufacturing; laser cladding deposition; electrochemical machining; anodic
dissolution; titanium alloy
1. Introduction
Titanium and its titanium alloys have a rather wide range of applications, such as avia-
tion, aerospace, navigation, medical implants and other high-end industrial manufacturing
fields [
1
,
2
]. The high specific strength, superior corrosion resistance and excellent biocom-
patibility of titanium alloys lead to their wide application in these fields [
3
]. Among them,
Ti6Al4V alloy is one of the most mature titanium alloys in application and research [
4
].
However, the ultrahigh chemical activity, large deformation and cutting resistance make
Ti6Al4V alloy a difficult material to machine [
5
]. Therefore, plenty of research focuses on
how to prepare titanium alloy parts with complex geometric structures, such as additive
manufacturing (AM) and special machining techniques.
Laser cladding deposition (LCD), a typical metal AM method, has the significant
advantages of no mold and near-net shape, and is especially suitable for the rapid manu-
facturing of difficult-to-machine materials [
6
,
7
]. The microstructure evolution, mechanical
properties and electrochemical corrosion properties of LCD-produced Ti6Al4V alloy have
received extensive attention. Wang et al. [
8
] found that the heterogeneous nucleation
on partially melted powders for equiaxed grains and the epitaxial growth from the pool
bottom for columnar grains are the two dominant solidification mechanisms during the
LCD process of Ti6Al4V alloy. Wu et al. [
9
] presented Ti6Al4V as being very susceptible to
Materials 2022, 15 , 3642. https://doi.org/10.3390/ma15103642 https://www.mdpi.com/journal/materials
