Metal Forging

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Available online at www.sciencedirect.com
journal homepage: www.elsevier.com/locate/jmrt
Original Article
The effect of thermal spraying on the forming

performance of incremental sheet forming
Yuanyu Liu a,b, Zijian Wang a,b, Yanle Li a,b,*, Hao Yuan a,b, Fangyi Li a,b
a
Key Laboratory of High Efficiency and Clean Mechanical Manufacture, Ministry of Education, School of Mechanical
Engineering, Shandong University, Jinan 250061, China
b
National Demonstration Center for Experimental Mechanical Engineering Education, Shandong University, Jinan
250061, China
article info abstrac
Article history: In order to reduce the manufacturing cycle and improve the forming performance of the
Received 6 December 2020 incremental sheet forming (ISF) process, a hybrid manufacturing process that combines
Accepted 5 March 2021 thermal spraying and incremental forming process was firstly proposed. The effects of
Available online 11 March 2021 different thermal spraying parameters on the forming properties and mechanical prop-
erties of sheet metal were investigated. Firstly, Fe316L coating was prepared on AA2024-T3
Keywords: plate by using atmospheric plasma thermal spraying, and then the plate is formed into the
Incremental sheet forming target shape with variable angles. In addition, tensile tests were carried out on the plates
Thermal spraying pretreated by thermal spraying with different parameters. The results showed that the
Mechanical properties yield strength of the plate decreased up to 70% and the elongation increased by 65% under
Forming properties the appropriate thermal spraying power. In the process of ISF, the axial forming force of
sheet metal after thermal spraying decreased obviously and the forming limit increased
obviously. In addition, influences of different processing steps (sand blasting and heating)
on the forming performance of sheet metal were investigated. It is found that the heating
effect in the thermal spraying process has the most obvious effect on the improvement of
forming performance, while the sand blasting process has adverse effect. Finally, in order
to optimize the thermal spraying area, the influence of thermal spraying at different areas
on the forming performance of sheet metal was investigated.
© 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC
BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
forming track to obtain the expected shape. Since Leszak [1]

1. Introduction introduced the concept of single incremental sheet forming in
1967, it has been attracted extensive interest both in academia
As a novel rapid prototyping technology, the incremental and industry fields [2]. The forming limit is an important index
sheet forming (ISF) process has the advantages of high form- to evaluate the formability of sheet metal, which reflects the
ing limit and flexible forming shape, which relies on the tool maximum deformation degree of sheet metal before plastic
head to deform the workpiece along the predetermined failure. How to improve the forming limit of sheet metal in
* Corresponding author.
E-mail address: yanle.li@sdu.edu.cn (Y. Li).
https://doi.org/10.1016/j.jmrt.2021.03.024
2238-7854/© 2021 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://
creativecommons.org/licenses/by-nc-nd/4.0/).
j o u r n a l o f m a t e r i a l s r e s e a r c h a n d t e c h n o l o g y 2 0 2 1 ; 1 2 : 7 7 6 e7 8 7 777
incremental sheet forming process and improve the forming technologies to be combined. Chang et al. [29] proposed the
quality is the research focus in this field [3]. concept of Additive/subtractive hybrid manufacturing
In order to improve the forming limit of sheet metal in the (ASHM). That is, the advantages of additive manufacturing
incremental sheet forming process, some scholars have tried and subtractive manufacturing are combined. Ambrogio et al.
various strategies such processes as process parameter opti- [30] chose laser sintering for local thickening prior to single
mization [4e6], multi-point ISF [7,8], and the multistage ISF point incremental forming and found that this combination of
[9,10]. In addition, hybrid ISF strategies, such as ultrasonic- processes could take advantages of both processes, thus
assisted ISF [11e13], electric-assisted ISF [14,15], laser- allowing more complex and/or higher quality parts to be
assisted ISF [16,17] and heat-assisted ISF [18e20] have been manufactured. In this paper, a production strategy combining
proposed. Mirnia et al. [21] used the combination of hydraulic additive and sheet forming technology is proposed, which
bulging and single point ISF to improve the forming limit. Mo combines ISF with additive manufacturing technology to
et al. [22] used electromagnetic-assisted ISF and stretching to improve the forming performance. Among the various addi-
deform large scale thin-wall ellipsoid parts. Li et al. [23] tive manufacturing technologies, thermal spraying technol-
studied the influence of the integral heating and local heating ogy has been widely applied in high-end technology fields
on the forming limit of materials, and found that the forming such as aerospace, ship, automobile, energy and electronics
limit is increased with the increase of temperature within the due to its characteristics of simple operation, high efficiency
investigated range. and flexible process. After decades of rapid development,
In recent years, additive manufacturing (AM) has been thermal spraying technology has become increasingly
applied to the manufacture of parts of various materials and mature. Thermal spraying technology can be used to prepare
sizes, and has been widely used in many fields. The use of AM coatings on the material surface with high hardness, high
technologies, in fact, is no longer confined to the production of strength, wear resistance, corrosion resistance, high temper-
models and prototypes [24]. Considering the advantages of ature oxidation resistance, insulation, radiation protection,
additive manufacturing, some scholars have proposed a wave absorption or selfelubrication properties [31,32].
composite manufacturing process that combines two or more Recently, Xu et al. [33] prepared a self-lubricating coating on
processes belonging to the same or different manufacturing pure titanium substrates by the atmospheric plasma spraying
categories [25,26]. In particular, AM techniques have been (APS) process before the forming process for improving the
used to produce rough parts, which are subsequently finished lubrication condition. To the best of authors’ knowledge, the
by machining [27]. Newman et al. [28], proposed a process attempt to combine the thermal spraying and incremental
planning method in conjunction with a developed framework sheet forming process for improving the formability has not
to enable the strengths of additive and subtractive been reported.
Table 1 e Experimental parameters.

No. Forming Pretreatment Pretreatment Thermal spraying Number of Powder
area power/kW coating layer material
1e1 (c) None (I)
1e2 (c) Thermal spraying (I) 25 2 Fe316L
2e1 (a) None (I)
2e2 (a) Only sandblasting (I)
2e3 (a) Only heating (I)
2e4 (a) Sandblasting and heating (I)
2e5 (b) None (I)
2e6 (b) Only sandblasting (I)
2e7 (b) Only heating (I)
2e8 (b) Sandblasting and heating (I)
3e1 (c) Thermal spraying (II) 25 2 Fe316L
3e7 (c) Thermal spraying (III) 25 2 Fe316L
778 j o u r n a l o f m a t e r i a l s r e s e a r c h a n d t e c h n o l o g y 2 0 2 1 ; 1 2 : 7 7 6 e7 8 7
Fig. 1 e The geometric dimensions of the target shaped parts: (a) truncated pyramid with a fixed angle; (b) truncated cone
with variable angle of 30e90 ; (c) truncated cone with variable angle of 30e85 .
Fig. 2 e Thermal sprayed areas of sheet metal.
investigated. Compared with the existing work, the main

Table 2 e Mechanical properties of original sheet.
contributions of the present work are as follows:
Elasticity Yield Tensile Elongation (%)
modulus/GPa strength/MPa strength/MPa
1) A hybrid manufacturing process that combines thermal
66.89 256.78 311.64 15.76 spraying and incremental forming process was proposed,
and the mechanical properties and forming performances
of the sheet after thermal spraying were analyzed.
Therefore, this paper explores the effects of different pro- 2) The influence of sandblasting and heating during thermal
cess parameters (thermal spraying power, thermal spraying spraying process on the ISF process was individually
layers) on the mechanical properties of plates. Then, the investigated by decomposing the steps of thermal spraying
forming performance of pretreated sheet in ISF was investi- process.
gated, and the influence of different processing steps of 3) The thermal spraying area of sheet metal was optimized.
thermal spraying on the forming properties of sheet was Thermal spraying with different parameters was carried
analyzed. In addition, the influence of different thermal out at different areas to explore the influence of spraying
spraying areas on the forming formability in ISF was area on sheet metal forming performances.
Fig. 3 e The morphology of Fe316L powder.

Fig. 4 e The experimental equipment of thermal spraying: (a) The controller of XM-80SK plasma spraying system; (b)
Kawasaki manipulator and the XM-80JZ plasma spray gun.
2. Experimental methods
2.1. Experimental design
In order to explore the influence of thermal spraying on the

incremental forming process, three sets of different experi-
ments were designed, and the specific setting of parameters
are shown in Table 1. In the first group of experiments, ther-
mal spraying process was combined with ISF. The power of
thermal spraying and the number of coating layer were
selected as variables to determine the best experimental pa-
rameters. Specifically, two layers are sprayed in quick suc-
cession, while four layers are sprayed twice with a cooling
period between each operation. The performance of coating
prepared by thermal spraying with different parameters and
forming properties of the treated sheets were investigated.
Test 1-1 was designed as a control test to clarify the effect of
Fig. 5 e The sheet after thermal spraying process.
thermal spraying on material properties. The sheet used in
test 1-1 was raw sheet without any treatment. The second
group of experiments was carried out to investigate the in-
fluence of different processing steps of thermal spraying
process on sheet properties, which was divided into two steps:
sandblasting and heating. Consequently, three different pre-
processing methods (sandblasting, heating, and sandblasting
and heating) were implemented. Two kinds of forming
shapes, the truncated pyramid and the truncated cone with
variable wall angles, were compared. The geometric di-
mensions are shown in Fig. 1a and b. The third group of ex-
periments is carried out to explore effects of two different
thermal spraying areas (as shown in Fig. 2) on the properties of
the sheet metal. The first area is a circle with a diameter of 40
mm, as shown in Fig. 1b. As shown in Fig. 1c, the sprayed area
is designed with an outer diameter of 120 mm and an inner
diameter of 90 mm which corresponds to the outer boundary
of the formed region. And this group of experiments can also
be used to examine the effect of the flame temperature at
Fig. 6 e The experimental equipment of ISF.
Fig. 7 e Tensile test sample and facility: (a) Dimensions of the testing sample; (b) Tensile testing machine.
different thermal spraying powers on thermal behavior of the properties of the original sheet is given in Table 2. Thermal
sheet metal. spraying powder is Fe316L stainless steel, and the particle size
is ranged between 40 and 50mm with the morphology of
2.2. Experimental materials powder shown in Fig. 3. The powder is dried to ensure the
powder has good fluidity and is easy to be evenly sent into the
Aluminum alloy 2024-T3 with a thickness of 2 mm was flame. Therefore, the spray particles have an ideal melting
selected as the substrate material, and the mechanical state.
Fig. 8 e SEM images of coatings prepared by different thermal spraying parameters: (a) 25 kW 2 layers; (b) 30 kW 2 layers; (c)
36 kW 2 layers; (d) 25 kW 4 layers; (e) 30 kW 4 layers; (f) 36 kW 4 layers.
55
Reduction rate of axial force/%

50
45
40
35
30
25
20 25kW-2 layers 25kW-4 layers

30kW-2 layers 30kW-4 layers
15 36kW-2 layers 36kW-4 layers
100 200 300 400 500

Time/s
Fig. 10 e The axial force reduction rates of the sheets

pretreated by thermal spraying during ISF.
Lubricate was employed to reduce the friction between the

tool and the plate. Throughout the forming process, a Kistler
dynamometer (model 9257B) was installed under the fixture to
measure the forming force.
In order to explore mechanical properties of the sheet after
thermal spraying, the sheets with or without thermal spraying
treatment were cut off for tensile tests. The INSTRON tensile
testing machine as shown in Fig. 7b was used for the test. The
tensile test sample was fabricated according to GB/T228-2002
national standard, and the dimensions was shown in Fig. 7a.
An extensometer is installed in the middle of the sample and
the tensile rate is 1 mm/s.
Fig. 9 e Mechanical properties of sheets pretreated by

thermal spraying with different process parameters: (a) 3. Results and discussion
Stressestrain curves; (b) Comparison of mechanical
properties. 3.1. Examination of the sprayed coating
As shown in Fig. 8, it can be seen that when the thermal

2.3. Experimental equipment
spraying power is 25 kW, the powder adhesion is poor and the
coating distribution is uneven. By contrast, when the thermal
The experimental equipment of thermal spraying (as shown
in Fig. 4) is a XM-80SK plasma spraying system, and the model
of the plasma spray gun is XM-80JZ. A six-axis manipulator
form Kawasaki (model RS020NFE20) is used to clamp the spray
gun. The gases used are nitrogen and argon. The pressure of
nitrogen is 0.71 MPa, and that of argon is 0.74 MPa. The powder
feeding method is scraper pressure type, and the powder
feeding gas is nitrogen and the pressure is 0.4e0.8 MPa. The
powder is pushed to the nozzle through the scraper under the
push of nitrogen, and the powder is delivered by a radial
external feeding. Fig. 5 shows the sheet after thermal spraying
process.
Before spraying, the sheet was sandblasted with 24 mesh
brown corundum. The experimental equipment of ISF (as
shown in Fig. 6) is a DAEWOO ACE-V500 vertical milling cen-
ter. The diameter of the hemispherical tool head is 10 mm and
the head material is tungsten carbide. The machine tool
spindle does not rotate during the forming process. The feed Fig. 11 e The axial forces of the sheets pretreated by
speed is 2000 mm/min and the step-down size is 0.2 mm. different processing steps during ISF.
Fig. 12 e The forming parts after break: (a) forming part without thermal spraying; (b) forming part with thermal spraying.
spraying power is increased to 30 kW and 36 kW, the coatings under different powers differs significantly, which indicates
are well prepared and evenly distributed. that 30 kW is the best spraying power of Fe316L stainless steel
At the thermal spraying power of 25 kW, particles can still powder. At 25 kW power, the flame temperature is low and the
be observed in the sprayed coating because the powder is not powder fails to reach the semi-melting state, resulting in low
in the semi-molten state due to insufficient heat. After powder utilization ratio and thin coating. At 36 kW power, the
spraying twice (four layers), the thickness distribution of the flame temperature is too high and spatter is generated due to
coating is more uniform at about 50 mm, but the maximum the excessive melt of the powder, resulting in the reduced
thickness is not significantly increased. By increasing the coating thickness.
thermal spraying power to 30 kW, most of the powders are
well melted, so the coating has no obvious granular shape,
3.2. Mechanical properties of sheets pretreated by
and the coating thickness prepared under this power is the
thermal spraying
largest. The coating thickness after a single spraying is about
200 mm, and it is about 400 mm after spraying four layers.
The measured stressestrain curves of sheets with or without
However, the surface quality of the coating is relatively poor
pretreated by thermal spraying are shown in Fig. 9a.
and the porosity is higher than that under 36 kW. When the
Compared with the original sheet which is shown as the
thermal spraying power is 36 kW, all the powders are nearly
dotted red line in Fig. 9b, the changes of specific mechanical
completely melted, and the porosity of coating is lower. After
properties of the treated sheets with different thermal
two times spraying, the thickness of the coating increases
spraying parameters are shown in Fig. 9b.
from 20 mm to 30 mm, but the stratification of coating prepared
As can be seen from Fig. 9, sheets are softened after ther-
by each spraying is obvious. The coating thickness prepared
mal spraying, which is manifested as a significant reduction in
the strength. This is because the temperature of sheet rises
under the action of the plasma flame during the thermal
25kW 2 layers 25kW 4 layers spraying process. The sheet strength decreases most obvi-
40 30kW 2 layers 30kW 4 layers ously with a 30 kW thermal spraying power, in which the yield
36kW 2 layers 36kW 4 layers
strength decreasing rate is up to 70% and the tensile strength
The forming depth/mm
decreasing rate is up to 55%. However, when the thermal

30 spraying power is relatively low (25 kW) or large (36 kW), the
reduction of sheet strength is not so significant. In terms of the
elongation, with a 25 kW thermal spraying power, the elon-
20 gation of the sheet is reduced by about 35% compared with the
original sheet, while the elongation is increased significantly
with higher thermal spraying powers (30 kW and 36 kW).
10 With the same thermal spraying power, different coating
layers correspond to different coating thicknesses distribu-
tion, resulting in the distinction of the mechanical properties
0 of the sheet. Specifically, the strength of the sheet with more
25kW 30kW 36kW
coating layers is lower with the spraying power of 25 kW,
Thermal spraying power
while no obvious difference is obtained for the strength of the
Fig. 13 e The forming depth of the sheets by different pre- sheet with different coating layers with thermal spraying
treatments during ISF. powers at 30 kW and 36 kW. Nevertheless, the elongation of
formed into truncated pyramids as shown in Fig. 1a, and the

axial forming forces are compared in Fig. 11.
By comparison, it can be seen that the axial forming force
of the sand-blasted sheet is the largest, which is about 47%
higher than that of the original sheet at the later forming
stage. This is because the impact of sand particles during the
sand-blasting process causes obvious plastic deformation on
the surface of the sheet, resulting in microstructure changes
such as grain refinement and dislocation. Thus, the strength
of the sheet is improved, and the axial forming force is
increased. The axial forming force for the heated only sheet is
smallest, which is 22% lower than that of the original sheet.
During the process of plasma flame heating, the surface
temperature of the sheet can reach 280 C. Therefore, the
sheet is softened and the strength is reduced, leading to the
reduction of the axial forming force. It is concluded that sand-
blasting and heating have opposite effect on the axial forming
Fig. 14 e The forming limits of the sheets pretreated by force of the sheet. Pretreated by both sand-blasting and
different process steps in ISF. heating, the axial forming force of the sheet is still lower than
that of the original sheet, but higher than that of the heated
only sheet. This suggests that heating plays a leading role in
the sheet with more coating layers is larger at all selected the axial forming force of sheet.
spraying powers. The difference of elongation is due to the
fact that a thicker coating can better compensate for the 3.4. Forming limits with different pre-treatments
thinning of the sheet during the stretching.
The sheets pretreated by different pre-treatments were
3.3. Forming forces with different pre-treatments formed into the truncated cone with the variable wall angle as
shown in Fig. 1c. During the ISF process, it stops when the
In the previous section, the effect of thermal spraying on sheet breaks. At this point, the total feed of the tool along the
mechanical properties of sheet metal was studied. This sec- vertical direction is the maximum forming depth, and it is
tion further investigates the effect of thermal spraying on used as the evaluation index of the forming limit. As is shown
forming forces in ISF. The axial forming force is the reaction in Fig. 12, large cracks were occurred for the forming parts
force along the forming tool axis which is an important indi- when it breaks. The experimental results of the forming depth
cator for evaluating the forming condition. Overall, the axial with different spraying pre-treatments are shown in Fig. 13.
forming force was significantly reduced after the sheet was As can be seen from Fig. 13, the forming limit of sheets
pretreated by the thermal spraying process. The reduction pretreated by thermal spraying are significantly increased
rate of axial force is the ratio of the axial forming force be- compared with the original sheet (test 1-1) which is 20.7 mm
tween the coated sheet and the raw sheet. represented by the red line. Generally, with the increase of the
It can be seen from Fig. 10 that the reduction ratio of axial spraying power, the forming limit decreases. The forming
force is largest (about 48% the later stage) with the spraying limit of the sheet pretreated by thermal spraying with the
power of 30 kW. This is because in the ISF process, the axial power of 25 kW is improved by about 70% compared with the
forming force is mainly determined by the strength of the original sheet. This is different from the decrease in elonga-
sheet. As discussed above, the strength is the lowest for the tion in the tensile test (Fig. 9). Under the same power, the
coated sheet with 30 kW spraying power. As can be seen from number of coating layer has little influence on the forming
Fig. 10, the reduction rate of axial forming force gradually in- limit of the sheet pretreated by thermal spraying.
creases with the processing time and finally tends to be stable. The sheets pretreated by different steps of spraying pro-
The number of coating layers also affects the force reduction cess were formed into the truncated cone with the variable
rate. With the power of 30 kW and 36 kW, the axial force wall angle as shown in Fig. 1b, and the forming limits are
reduction rate of two layers is relatively larger than that of shown in Fig. 14.
four layers, but this is opposite with the power of 25 kW. This It is obtained that the forming limit of sheet pretreated by
is because the thickness of the sheet with more coating layers sand-blasting only is reduced, which is because the sheet
is larger, which leads to the greater bending resistance of the surface is hardened and the strain induced dislocation density
sheet, and the less prone to bending deformation. As shown in is increased in this condition [34], On the contrary, heating
Fig. 9b, when the thermal spraying power is 25 kW, the treatment helps to improve the forming limit. This is consis-
strength of four layers coated sheet is significantly lower than tent with the previous finding that the heating reduces the
that of two layers coated sheet. strength and the axial forming force. It is concluded that sand-
Furthermore, the influence of different spraying process- blasting and heating also have opposite effect on the forming
ing steps on the axial forming force during ISF is explored. The limit of the sheet. Furthermore, the forming limit of sheet
sheets pretreated under various conditions (i.e. heating only, pretreated by sand-blasting and heating is between the sheet
sand-blasting only and sand-blasting and heating) were only sand-blasted or only heated. Meanwhile, it is noted that
Table 3 e ISF experimental results of sheets thermal sprayed in different area.

No. Pretreated Thermal spraying Number Stable axial forming Forming
area power/kW of layer force/N depth/mm
1e2 25 2 2023 38.4
1e3 25 4 1827 38.9
1e4 30 2 1405 34.6
1e5 30 4 1433 35.5
1e6 36 2 1827 26.2
1e7 36 4 1911 26.7
3e1 25 2 1472 33.6
3e2 25 4 1496 34.3
3e3 30 2 1435 30.3
3e4 30 4 1458 30.8
3e5 36 2 1462 24.6
3e6 36 4 1490 24.9

Table 3 e (continued )
No. Pretreated Thermal spraying Number Stable axial forming Forming
area power/kW of layer force/N depth/mm
3e7 25 2 1558 37.6
3e8 25 4 1571 37.3
3e9 30 2 1568 37.5
3e10 30 4 1576 37.9
3e11 36 2 1579 37.4
3e12 36 4 1567 37.5
the sheet pretreated by both sand-blasting and heating shows 80%. Since there is no overlap between the thermal spraying
higher forming limit than the original sheet. This indicates area and the forming area, the forming area of sheet is only
that the influence of the heating on the forming limit of sheet affected by the heat of plasma flam and has little relation with
is more pronounced than that of the sand-blasting. coating properties. Therefore, it can be determined that
different thermal spraying parameters have the same effect
3.5. Optimization of thermal spraying area
In order to further optimize the composite process of thermal

spraying and incremental sheet forming, this section explores
the influence of thermal spraying area on axial forming force
and forming limit. The sheets were coated at different areas
(Fig. 2) and then were formed to truncated cones with variable
wall angles (Fig. 1c). The measured stable axial forming force
and the forming depth with different experimental conditions
are recorded in Table 3.
For the sheet thermal sprayed at the central deformed area
as shown in Fig. 2(II), the stable axial forming force is at the
same level around 1450 N, while the forming depth is varied
with different spraying parameters. Specifically, the forming
depth decreases with the increase of the thermal spraying
power, this is consistent with the results from Fig. 15. For the
sheet thermal sprayed at the outer region of the deformed
area as shown in Fig. 2(III), there is no significant difference for
both the stable axial forming force and the forming limit of
sheets thermal sprayed by different parameters. Compared
with the original sheet, the stable axial forming force is Fig. 15 e The forming limits of the sheets thermal sprayed
reduced by 45%, and the forming limit is increased by about in different area in ISF.
on the heating. It is concluded that different properties of the

coatings prepared by different thermal spraying parameters Declaration of Competing Interest
are the main factors that cause the change of sheet properties.
Generally, the stable axial forming force obtained with the The authors declare that they have no known competing
sheet sprayed at the central area (II) is lower than that of the financial interests.
sheet sprayed at the outer ring area (III). This is due to the
change of the rigidity of the sheet due to the forming process.
Meanwhile, compared with the sheet sprayed at the central Acknowledgement
area (II), the forming limit is higher for the sheet sprayed at the
outer ring area (III). This is attributed to the combined effect of This work is supported by National Natural Science Founda-
the sheet heating and the change of sheet property. tion of China (51975328), Project funded by China Postdoctoral
Science Foundation (2020M682203) and Young Scholars Pro-
gram of Shandong University (2018WLJH55).
4. Conclusions
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Metal Forging

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j o u r n a l o f m a t e r i a l s r e s e a r c h a n d t e c h n o l o g y 2 0 2 1 ; 1 2 : 7 7 6 e7 8 7

Available online at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/jmrt

The effect of thermal spraying on the forming

article info abstrac

forming track to obtain the expected shape. Since Leszak [1]

Table 1 e Experimental parameters.

Fig. 2 e Thermal sprayed areas of sheet metal.

investigated. Compared with the existing work, the main

Fig. 3 e The morphology of Fe316L powder.

2.1. Experimental design

In order to explore the influence of thermal spraying on the

Reduction rate of axial force/%

20 25kW-2 layers 25kW-4 layers

100 200 300 400 500

Fig. 10 e The axial force reduction rates of the sheets

Lubricate was employed to reduce the friction between the

Fig. 9 e Mechanical properties of sheets pretreated by

As shown in Fig. 8, it can be seen that when the thermal

decreasing rate is up to 55%. However, when the thermal

formed into truncated pyramids as shown in Fig. 1a, and the

Table 3 e ISF experimental results of sheets thermal sprayed in different area.

1e3 25 4 1827 38.9

1e4 30 2 1405 34.6

1e5 30 4 1433 35.5

1e6 36 2 1827 26.2

1e7 36 4 1911 26.7

3e1 25 2 1472 33.6

3e2 25 4 1496 34.3

3e3 30 2 1435 30.3

3e4 30 4 1458 30.8

3e5 36 2 1462 24.6

3e6 36 4 1490 24.9

3e8 25 4 1571 37.3

3e9 30 2 1568 37.5

3e10 30 4 1576 37.9

3e11 36 2 1579 37.4

3e12 36 4 1567 37.5

In order to further optimize the composite process of thermal

on the heating. It is concluded that different properties of the

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