Content uploaded by Zhang Yisheng
Author content
All content in this area was uploaded by Zhang Yisheng on Feb 24, 2016
Content may be subject to copyright.
ORIGINAL PAPER
Investigation on Tribological Behavior of Advanced High
Strength Steels: Influence of Hot Stamping Process Parameters
Xiaowei Tian •Yisheng Zhang •Jian Li
Received: 18 August 2011 / Accepted: 29 December 2011 / Published online: 10 January 2012
ÓSpringer Science+Business Media, LLC 2012
Abstract In order to investigate the friction and wear
behavior of high strength steel in hot stamping process, a hot
strip drawing tribo-simulator is developed and the friction
coefficient, which is an important parameter in the finite
element modeling, is measured. The results have shown that
the friction coefficient remains almost unchanged until
temperature reaches 500 °C. It then increases sharply as
temperature is increased from 500 to 600 °C. It has also been
shown that the friction coefficient decreases as the drawing
speed increases. The change in the dominate wear mecha-
nism as the temperature and the drawing speed increases has
been identified from SEM analyses of the worn surface. The
dominate wear mechanism is the groove cutting at temper-
atures between room temperature and 500 °C, which chan-
ges to the adhesive wear at temperatures above 500 °C. The
main wear mechanism is the adhesive wear at 25 mm/s,
which changes to the slight groove cutting at 75 mm/s.
Keywords Friction and wear High strength steel Hot
stamping Adhesion Finite element modeling
1 Introduction
High strength steels (HSS) are a very important class of
materials for reducing the weight of vehicles, which, as a
result, leads to improvement in fuel efficiency, safety and
environment protection [1]. In recent years, hot stamping of
HSS has played an important role in the development of
future generation of ground vehicles, because this process
can bring the combined benefits of maintaining the high
strength of the steel and lowering the spring back of the
workpiece when operated at elevated temperatures [2].
However, a major problem in forming of HSS is the galling
of the die and the scoring of the workpiece as a result of the
high contact pressure and temperature at the tool–work-
piece interface [3]. Solving this problem requires the proper
design of parameters for the hot stamping process and
detailed analysis on wear of the tool steel and attrition of the
sheet metal. And the finite element (FE) method is effective
in designing the processing parameters and predicting the
property of the final product. However, the numerical
results can be strongly influenced by the contact conditions
between the die and blank and the friction coefficient can
affect the metal flow, which, in turn, affects the molding
efficiency and quality [4–6]. Therefore, the variation trend
of the friction coefficient along with that of temperature and
velocity means a lot to the accuracy of FE simulation.
Extensive tribological research had been made on the
HSS. A new slider type of test system has been developed
to study the performance of several alternative die mate-
rials sliding against the advanced HSS [7] and to evaluate
the performance of several kinds of coatings and lubricants
[8]. Twist compression test (TCT) [9], ball-on-disk test
[10], SOFS tribometer (disc-shaped tools sliding against a
teal sheet surface) test [11] and deep drawing test [12],
ironing test [13], a tensile strip test [14] have been used to
investigate the galling in forming the HSS. However, all of
the experiments mentioned above are performed at the
room temperature. Many experiments have also been car-
ried out when the sheet metal is heated to up to 800 °C.
For instance, a Schwingung Reibung Verschlei machine
(SRV b: reciprocating friction and wear) has been used to
X. Tian Y. Zhang (&)J. Li
State Key Laboratory of Material Processing and Die and Mould
Technology, College of Materials Science and Engineering,
Huazhong University of Science & Technology, Luoyu Road,
Wuhan 430074, China
e-mail: zhangys@mail.hust.edu.cn
123
Tribol Lett (2012) 45:489–495
DOI 10.1007/s11249-011-9908-1
investigate the fundamental friction and wear behavior
under different temperatures and sliding rates [15] and to
assess different tool materials [16]. A tribo-simulator for
hot stamping has been developed to evaluate the coeffi-
cients of friction. A hot strip drawing simulator has been
used in a study on the friction and wear between tool steel
and Al–Si-coated boron steel sheet at elevated tempera-
tures [17,18]. Cup deep drawing tests at elevated tem-
peratures have been made to evaluate the friction
coefficient lfor the direct hot stamping process of boron–
manganese steels [19].
This article focuses on measuring the friction coefficient of
the high strength steel at elevated temperatures and on
investigating the variation tendency and the friction mecha-
nism. An induction heating strip drawing tribo-simulator is
built to investigate the wear of the die and the scorching of the
sheet metal at different drawing speedsand temperatures, and
hence to simulate the hot stamping process parameters.
Moreover, the morphology of the surfaces worn at different
test temperatures and speeds are analyzed to understand the
wear behaviorand wear mechanisms of the high strength steel.
2 Experimental
2.1 Testing System
Figure 1shows a schematic diagram of the hot strip drawing
tribo-simulator. The induction heating was used to ensure
high heating rate and hence less oxidation of the strip,
alleviating the adverse effect on experimental results. The
temperature was measured by a thermal infrared imager
(FLIR 320A). A load sensor (error 0.5%) was mounted on the
mechanical loading device to measure the drawing force, and
strain gages (error below ±0.15%) were fixed on the device
to measure the friction force. The measured data were col-
lected by a precise NI USB6008 DAQ card (12bit ADC,
10 ks/s). The drawing speed was regulated by a servo control
system (Leadshine ACM602V26-2500). The friction coef-
ficient was calculated from the relationship l=f/F
D
, where
f is the friction force and F
D
is the pressure force, both of
which were measured directly to guarantee accurately cal-
culated results of the friction coefficient. Specific machine
parameters used are listed in Table 1.
2.2 Materials
Tool steel H13 was selected for fabrication of the top and
bottom friction components that generate friction with the
hot steel strip. A proprietary high strength steel Advanced
1500 was used as the sample for friction measurement. The
chemical composition and room temperature hardness of
the steels are listed in Table 2. Figure 2shows the
dimension of the top friction component. The dimension of
the friction strip samples is 80 915 91.5 mm.
2.3 Measurement of Friction Coefficient
Friction coefficient as functions of temperature and drawing
speed was measured, respectively, to simulate the hot
Fig. 1 Schematic
representation of hot strip
drawing tribo-simulator
Table 1 List of specifications of hot drawing simulator
Heating temperature Drawing speed Compression Force Heating rate Drawing distance
Max. 1,000 °C Max. 150 mm/s Max. 500 N Max. 400 °C/s Max. 600 mm
Table 2 The chemical composition in (wt%) and mechanical properties of the tool (H13) and workpiece material (Advanced 1500)
Material C Mn Si B P S Ti Mo V Hardness (HV)
Advanced 1500 0.2 1.64 0.85 0.001 0.005 0.001 0.022 0.01 – 210
H13 0.4 0.3 1.1 –B0.03 B0.03 – 1.5 1.2 560
490 Tribol Lett (2012) 45:489–495
123
stamping processes. And a constant load of 215 N was
applied for all the measurements. Table 3shows the exper-
imental parameters. Each experiment was proceeded in the
following procedures: (1) polishing the surface of steel strip
samples and the friction components with a Buehler metal-
lographic machine up to 800 grid and then ultrasonically
cleaning them in acetone for 5 min; (2) inductively heating
the sample clamped on the servo tension device; (3) applying
load to the strip sample; (4) pulling the heated sample under
load at constant speed; and (5) acquisiting and recording data
by using a computer. The friction components were polished
repeatedly for every experiment to ensure the consistence of
surface contact.
2.4 Surface Characterization
The microstructure of the worn surfaces of the strip sam-
ples tested under various conditions was examined by an
electron scanning microscope (SEM, QUANTA 200). And
the surface roughness was measured by using a scanning
probe microscopy (SEIKO SPA400).
3 Results and Discussion
Figure 3, as an example, shows experimentally obtained
compression force, friction force, and friction coefficient
along the drawing distance for the sample that was heated
to 600 °C and drawn at a speed of 50 mm/s under a fixed
compression force of 215 N. It is seen that the compression
force exerted by the load device was very stable during the
period of drawing. However, the friction force and in turn
the friction coefficient oscillates point by point within a
moving distance of 50 mm with an average friction coef-
ficient of 0.34. As shown in Fig. 4, the temperature of the
sample was monitored by a thermal infrared imager at the
spot Sp1 that is very close to the friction components
(Fig. 4a), and it is confirmed that a relatively uniform and
stable sample temperature was maintained by the high
frequency induction heating device (Fig. 4b).
3.1 Effect of Temperature
Figure 5shows the friction coefficient of the steel along the
sliding distance (Fig. 5a) and the average friction coeffi-
cient (Fig. 5b) at various temperatures between room
temperature and 700 °C. As a matter of fact, such mea-
sured friction coefficient is not the absolute friction coef-
ficient that is a characteristic property of the steel, instead,
is the apparent friction coefficient that is affected by the
contact area between the sliding components and the ware
of the steel strip occurred during the sliding. At room
temperature, the friction coefficient decreased from 0.3 to
0.2 after the sliding of 10 mm and then stabilized at about
0.2. This might because of the fact that the contacting
surface area between the friction components and the steel
strip was smaller at the beginning so that the contact
pressure was higher and the wear was correspondingly
much more severe. However, after a period of running the
contacting surfaces became much smoother and hence the
friction and wear became more stable. Similar trend of
friction coefficient variation was obtained for the steel at
500 °C. At high temperatures, the trend for friction coef-
ficient variation with the sliding distance was not so
Fig. 3 The compression force, friction force, and friction coefficient
along a drawing distance of 50 mm at 600 °C and a drawing speed of
50 mm/s
Fig. 2 Schematic
representation of tool dimension
Table 3 Experimental parameters for measurement of friction
coefficient
Temperature
(°C)
Drawing
speed (mm/s)
Room temperature 50
500 50
550 25
75
600 50
700 50
Tribol Lett (2012) 45:489–495 491
123
obvious due to the correspondingly lower hardness and
strength of the steel strip which ensures a larger contact
surface area at the beginning of sliding and leads to ran-
domly formed adhering points between the sliding com-
ponents and more severe ware on the steel surface. The
mean friction coefficient of the steel was about 0.25 at
temperatures up to 500 °C. It surged to 0.34 at 600 °C,
indicating the occurrence of severe adhesive wear. It fur-
ther increased to 0.41 at 700 °C because of the combined
effect of ductile tear and serious adhesive wear at this
higher temperature. It is clear that the critical temperature
that initiated massive adhesive wear was 600 °C.
Figure 6shows the SEM surface microstructure of the
steel strips tested at different temperatures. Slided at room
temperature the worn surface consisted of smooth and
narrow grooves (Fig. 6a). The dominant wear mechanism
is the cutting of the grooves. At 500 °C, the grooves were
relatively shallow and wide with coarse edges and a small
degree of adhere wear was noted with the formation of
shear wedges (Fig. 6b). However, the worn surface at
600 °C constituted shallow grooves and many peeling pits,
suggesting that the main wear mechanism was severe
adhesion associated with the formation of ‘‘shear wedges
pattern.’’ And at 700 °C, severe ductile tear was found at
the left side of Fig. 6d, and also there was massive plastic
deformation, indicating serious adhesive wear. These
microstructure observations are consistent with the surface
roughness measurement which indicates that the surface
roughness (Ra) is 0.23, 0.25, 0.33, and 0.36 lm for the
steel strips tested at room temperature, 500, 600, and
700 °C, respectively, and are supportive to the above
analysis made from the obtained friction coefficient results.
The reason for the sudden increase of the adhesive wear
from 500 to 600 °C can be explained by the fact that the
yield and tensile strength of steel Advanced 1500 is much
higher at 500 °C than at 600 and 700 °C[20], which means
that the plastic deformation is more difficult and the
adhesive wear is less prone to occur at 500 °C. The ductile
tear observed at 700 °C can also be attributed to its lower
tensile strength at this temperature.
3.2 Effect of Drawing Speed
The dependence of friction coefficient on the drawing
distance at constant temperature of 550 °C and drawing
speeds of 25 and 75 mm/s are shown in Fig. 7, with
Fig. 4 The thermal image
obtained by a thermal infrared
imager (a) and the temperature
variation of the fixed spot Sp1
(b) within a moving distance of
50 mm
Fig. 5 The friction coefficient of steel Advanced 1500 along the moving distance (a) and the average friction coefficient at temperatures (b)of
room temperature, 500 °C, 600 °C and 700 °C
492 Tribol Lett (2012) 45:489–495
123
average values of 0.48 and 0.35, respectively. When the
drawing speed was 25 mm/s, the friction coefficient rose
and then deceased to a stable value; and at 75 mm/s, the
friction coefficient values were much lower than those
measured at 25 mm/s. Thus, this result suggests that at high
temperature lowering the drawing speed at a constant
temperature may have the same effect as increasing the
temperature at a constant drawing speed (Fig. 5), that is,
increasing the possibility of adhesive wear and in turn the
friction coefficient. This expectation is supported by the
fact that the value of friction coefficient at 550 °C and
25 mm/s is higher than those at 600 °C and 50 mm/s and
550 °C and 75 mm/s. Figure 8shows the SEM images of
the worn surface of the steel strips at 550 °C and different
drawing speeds. The worn surface at 25 mm/s (Fig. 8a)
consisted of features of massive plastic deformation with
shear wedge pattern, confirming the occurrence of severe
adhesive wear; the edges of the grooves were also rela-
tively coarse. However, when the drawing speed was
increased to 75 mm/s (Fig. 8b), the grooves were shallow
and slight and the edges of the grooves were smooth
without noticeable adhesive wear. These microstructure
examinations also indicate that the wear was more severe at
a slower drawing speed at the same temperature and
pressure. This may be explained by considering that the
contact time of the friction components with the steel strip
is longer at a slower speed, which offered enough time for
forming the adhering points at which the plastic deforma-
tion occurs on sliding. However, formation of the adhering
points is much more difficult in a very short period of
contact time when the speed is much higher.
Fig. 6 SEM microstructure of worn surfaces of the steel strips tested at aroom temperature, b500 °C, c600 °C, and d700 °C
Fig. 7 Friction coefficient as a function of sliding distance at 550 °C
and various drawing speeds
Tribol Lett (2012) 45:489–495 493
123
4 Conclusions
Experimental studies pertaining to the tribological behavior of
an high strength steel Advanced 1500 have been made using
the hot drawing tribo-simulator under different temperatures
and drawing speeds and some new results have been obtained.
The techniques provided by the hot drawing tribo-simulator
proved to be both efficient and effective for such studies. The
results obtained indicate that temperature and drawing speed
can considerably influence the friction and wear behavior
during the tribological contact of the high strength steel with
the friction components. At 500 °C and 50 mm/s, the friction
coefficient is much the same as that at room temperature, and
the main wear mechanism are the groove cutting. With a
constant drawing speed of 50 mm/s, the critical temperature
for the occurrence of massive adhesive wear is 600 °Cat
which the friction coefficient starts to increase greatly. The
friction coefficient measured at a lower drawing speed is
higher than that measured at a higher drawing speed. At
25 mm/s, the main wear mechanism is adhesive wear,
whereas, at 75 mm/s, only slight grooves present on the worn
surface. The friction coefficients measured can be used in the
FE modeling to enhance the accuracy of the simulation and
hence to obtain the more realistic metal flowing and forming
pattern. Moreover, the test result can guide the actual pro-
duction to choose the reasonable process parameter such as
heating temperature and punching speed to releaserates of die
wear and the scratching on the productions.
Acknowledgment This study was supported by National Basic
Research Program of China (973 Program) under the contract No.
2010CB630803.
References
1. Zhu, B., Zhang, Y., Li, J., Wang, H., et al.: Simulation research of
hot stamping and phase transition of automotive high strength
steel. Mater. Res. Innov 15(1), s426 (2011)
2. Ozturk, F., Toros, S., Kilic, S.: Tensile and Spring-Back Behavior
of DP600 Advanced high strength steel at warm temperatures.
J. Iron Steel Res. Int 16(6), 41–46 (2009)
3. Borsetto, F., Ghiotti, A., Bruschi, S.: Investigation of the high
strength steel Al–Si coating during hot stamping operations. Key
Eng. Mater. 289, 289–296 (2009)
4. Behrens, A., Schafstall, H.: 2D and 3D simulation of complex
multistage forging processes by use of adaptive friction coeffi-
cient. J Mater. Process. Technol. 80–81, 298–303 (1998)
5. Al-Mayah, A., Soudki, K., Plumtree, A.: FEM and mathematical
models of the interfacial contact behaviour of CFRP-metal cou-
ples. Compos Struct 73(1), 33–40 (2006)
6. Jiang, Z.Y., Tieu, A.K., Zhang, X.M.: Finite element modelling
of mixed film lubrication in cold strip rolling. J. Mater. Process.
Technol. 151(1–3), 242–247 (2004)
7. Cora, O.N., Koc, M.: Experimental investigations on wear
resistance characteristics of alternative die materials for stamping
of advanced high-strength steels (AHSS). Int. J. Mach. Tools
Manuf. 49(12–13), 897–905 (2009)
8. Cora, O
¨.N., Namiki, K., Koc¸, M.: Wear performance assessment
of alternative stamping die materials utilizing a novel test system.
Wear 267(5–8), 1123–1129 (2009)
9. Kim, H., Sung, J.H., Goodwin, F.E., Altan, T.: Investigation of
galling in forming galvanized advanced high strength steels
(AHSSs) using the twist compression test (TCT). J. Mater. Pro-
cess. Technol. 205(1–3), 459–468 (2008)
10. Sresomroeng, B., Premanond, V., Kaewtatip, P., Khantachawana,
A., et al.: Anti-adhesion performance of various nitride and DLC
films against high strength steel in metal forming operation.
Diam. Relat. Mater. 19(7–9), 833–836 (2010)
11. Ga
˚a
˚rd, A., Krakhmalev, P., Bergstro
¨m, J.: Wear mechanisms in
galling: cold work tool materials sliding against high-strength
carbon steel sheets. Tribol. Lett. 33(1), 45–53 (2009)
12. Sresomroeng, B., Premanond, V., Kaewtatip, P., Khantachawana,
A., et al.: Performance of CrN radical nitrided tools on deep
drawing of advanced high strength steel. Surf. Coat. Technol.
205(17–18), 4198–4204 (2011)
13. Kim, H., Han, S., Yan, Q., Altan, T.: Evaluation of tool materials,
coatings and lubricants in forming galvanized advanced high strength
steels (AHSS). Cirp Ann. Manuf. Technol. 57(1), 299–304 (2008)
14. Lovell, M.R., Deng, Z.: Characterization of interfacial friction in
coated sheet steels: influence of stamping process parameters and
wear mechanisms. Tribol. Int. 35(2), 85–95 (2002)
15. Hardell, J., Kassfeldt, E., Prakash, B.: Friction and wear behav-
iour of high strength boron steel at elevated temperatures of up to
800 degrees C. Wear 264(9–10), 788–799 (2008)
Fig. 8 SEM images of the worn surface of the steel strips tested at 25 mm/s (a) and 75 mm/s (b)
494 Tribol Lett (2012) 45:489–495
123
16. Hardell, J., Prakash, B.: High-temperature friction and wear
behaviour of different tool steels during sliding against Al–Si-
coated high-strength steel. Tribol. Int. 41(7), 663–671 (2008)
17. Yanagida, A., Azushima, A.: Evaluation of coefficients of friction
in hot stamping by hot flat drawing test. Cirp Ann. Manuf.
Technol. 58(1), 247–250 (2009)
18. Yanagida, A., Kurihara, T., Azushima, A.: Development of tribo-
simulator for hot stamping. J. Mater. Process. Technol. 210(3),
456–460 (2010)
19. Kondratiuk, J., Kuhn, P.: Tribological investigation on friction
and wear behaviour of coatings for hot sheet metal forming. Wear
270(11–12), 839–849 (2011)
20. Shi, Z., Liu, K., Wang, M., Shi, J., et al.: Thermo-mechanical
properties of ultra high strength steel 22SiMn2TiB at elevated
temperature. Mater. Sci. Eng. A 528(10–11), 3681–3688 (2011)
Tribol Lett (2012) 45:489–495 495
123
