1) Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China 2) Thermal Spray Center (CPT), University of Barcelona, Barcelona 08028, Spain;;
Cite this article:
Guanglu MA, Xinyu CUI, Yanfang SHEN, CINCA Nuria, M. GUILEMANY Josep, Tianying XIONG. INFLUENCE OF SUBSTRATE MECHANICAL PROPER-TIES ON DEPOSITION BEHAVIOUR OF 316L STAINLESS STEEL POWDER. Acta Metall Sin, 2016, 52(12): 1610-1618.
Nowadays the theory of critical velocity of particles in cold spray has been already accepted generally. In the familiar semi-empirical formulas of the theory, only the properties and conditions of particles have been considered but there is no consideration of substrate. Yet most researches for effect of substrates' properties implied hardness of substrate was the most essential. However, little attention has been devoted to influence of other mechanical properties (e.g. Young's modulus and Poisson's ratio) and their cooperation on the deposition behavior. In order to study the effect systematically, 316L stainless steel particles were deposited by wipe test on six different substrates with a widely range of mechanical properties including Young's modulus, hardness and Poisson's ratio. They are pure Al, pure Cu, 7075T6 Al alloy, mild steel, Inconel625 and Ti6Al4V. The specimens have been investigated from morphology, cross-section and deposition efficiency. It is found that not only hardness but also Young's modulus and Poisson's ratio can affect deformation and deposition of bonded particles through playing a role in energy partition and bonding mechanism. In the case, the deformation of deposited particles is dependent on energy accepted by the particles, while the deposition efficiency is related to the bonding mechanism and energy accepted by substrate. According to the deformation level of the deposited particles, there are two kinds of substrate materials. On the one hand, bonding between particles with little deformation and their substrates is mainly dependent on mechanical interlock, in which both hardness and Young′s modulus of the substrates are lower than that of the particle. Then a parameter, Epara, has been calculated to predict the tendency of deposition efficiency for the situations. AZ91 alloy has been employed as substrate material in confirmatory experiment. Its result indicates that Epara is available for tendency prediction of the deposition efficiency of spherical-like deposited particle. On the other hand, the bonding mechanism of deposited particle with obviously flattening is more complex. In this situation, either hardness or Young′s modulus of the substrates is higher than that of the particle. The more area of fresh metal contacts on the interface, the higher deposition efficiency is.
Fig.1 SEM image (a) and particle size distribution (b) of 316L stainless steel feedstock powder
Fig.2 SEM images of as-sprayed single 316L particles on pure Al (a), pure Cu (b), AISI1015 mild steel (c), 7075T6 Al alloy (d), Inconel625 (e) and Ti6Al4V (f) (Spray condition: 800 ℃, 3.5 MPa)
Fig.3 Cross section SEM images of 316L particles deposited on pure Al (a), pure Cu (b), AISI1015 mild steel (c), 7075T6 Al alloy (d), Inconel625 (e) and Ti6Al4V (f) (l—long axis diameter of particle. Spray condition: 800 ℃, 3.5 MPa)
Material
Hardness
Young's
Poisson's ratio
Rf
Rd / %
HV
modulus / GPa
316L
199
190
0.30
Al
27
69
0.33
1.10±0.10
96.2±2
Cu
98
120
0.34
1.38±0.20
95.5±2
AISI1015
150
205
0.29
1.64±0.20
86.9±4
7075T6
181
71
0.33
1.25±0.05
20.9±6
Inconel625
276
207
0.31
1.62±0.20
96.5±2
Ti6Al4V
352
114
0.34
1.88±0.20
95.9±3
AZ91
72
45
0.35
55.0±6
Table 1 Mechanical properties of materials, flattening ratios (Rf) and deposition efficiencies (Rd) of 316L stainless steel particles on different substrates (800 ℃, 3.5 MPa )
Fig.4 Graphic of comparison of Rd and Epara vs hardness (a) and Young's modulus (b) for 316L stainless steel particles on weak substrates
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