G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
351–358
DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE
HOT-WORK TOOL STEEL
OBRABNA ODPORNOST ORODNEGA JEKLA ZA DELO V
VRO^EM AISI H11 PRI SUHEM DRSNEM KONTAKTU
Ga{per Pu{, Borut @u`ek, Agnieszka Zuzanna Gu{tin, Bojan Podgornik
Institute of Metals and Technology, Lepi pot 11, 1000, Ljubljana, Slovenia
Prejem rokopisa – received: 2023-05-22; sprejem za objavo – accepted for publication: 2023-06-26
doi:10.17222/mit.2023.880
This study focused on analyzing the tribological properties of AISI H11-type hot-work tool steel and how these properties de-
pend on the heat-treatment parameters. The investigation focuses on the abrasive wear resistance under different contact condi-
tions and correlations between the mechanical properties and the wear resistance. The results of the experiments show the im-
portance of proper austenitizing- and tempering-temperature selection, thus providing the optimal combination of tool hardness,
strength, and toughness. The coefficient of friction under dry-sliding-contact conditions and abrasive wear mode was found to
be largely independent of the heat-treatment conditions and more determined by the contact conditions, especially the load. On
the other hand, hardness and strength are the dominant mechanical properties controlling the abrasive wear resistance of the
hot-work tool steel.
Keywords: hot-work tool steel, friction, sliding wear, mechanical properties
[tudija predstavlja analizo tribolo{kih lastnosti jekla za delo v vro~em AISI H11 in kako so le-te odvisne od razli~nih
parametrov toplotne obdelave. Predstavljena raziskava se osredoto~a na abrazivno obrabno odpornost pri razli~nih kontaktnih
pogojih ter na korelacije med mehanskimi in obrabnimi lastnostmi. Rezultati eksperimentov ka`ejo na pomembnost izbire
pravilne temperature avstenitizacije in temperature popu{~anja, ki zagotavlja optimalno kombinacijo trdote, trdnosti in `ilavosti
orodja. Ugotovljeno je bilo, da je koeficient trenja pri pogojih suhega drsnega kontakta in na~inu abrazivne obrabe v veliki meri
neodvisen od pogojev toplotne obdelave in veliko bolj odvisen od kontaktnih pogojev, zlasti obremenitve. Izka`e se, da sta
trdota in trdnost prevladujo~i mehanski veli~ini, ki nadzorujeta abrazivno odpornost orodnega jekla za delo v vro~em.
Klju~ne besede: orodno jeklo, trenje, mehanske lastnosti materiala
1 INTRODUCTION
Forming tools are exposed to a combination of com-
plex loads during operation in industrial processes, such
as wear, plastic deformation and fatigue. These complex
loads can result in tool damage and failure. To ade-
quately address the loading and consequently the associ-
ated problems, a large set of material properties need to
be known, as well as how these properties depend on
heat-treatment processes and how they are interrelated.
Although the main selection criterion in the tooling in-
dustry is hardness, there are also other mechanical prop-
erties being equally or often even more important when
taking the final application into account. The properties
required to successfully characterize tool performance
and durability include toughness, strain-hardening expo-
nent, compressive and bending strength.
1–3
Contact surfaces between two bodies are not ideal,
consisting of imperfections, such as surface roughness,
inclusions, oxide layers, etc. The same is true for tools,
where already very high contact loads and a large degree
of plastic deformation lead to high stress concentrations
and large amounts of wear. Consequently, a tool’s con-
tact surfaces are exposed to a complex loading situation
during forming process, including chemical, thermal,
mechanical and tribological loadings. These loads
mainly come as a consequence of a sliding contact with a
work material that undergoes a transformation process,
high contact loads and temperatures, which finally result
in tool wear. Thus, wear comes as a sum of different
mechanisms, comprising crack initiation and propaga-
tion, thermal and mechanical fatigue, plastic deformation
as well as failures in the form of erosion, corrosion, abra-
sive or adhesive wear.
4,5
A very important aspect in the forming and tool in-
dustry is tool heat treatment and the selection of a proper
heat-treatment procedure and parameters to obtain the
best combination of mechanical, thermal, tribological
and fatigue properties of the tool. Without proper heat
treatment, the quality and functionality of the tool may
be degraded to the point where it becomes defective and
unusable. A correctly designed heat-treatment process,
being dependent on the tool steel chemical composition,
ensures that the tool functions according to the design
and intent, and that it meets all the performance specifi-
cations.
6,7
The aim of our investigation was to analyse the
tribological properties of H11-type hot-work tool steel
Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358 351
UDK 669.1:531.44:52-334.2 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 57(4)351(2023)
*Corresponding author's e-mail:
gasper.pus@imt.si

and how these properties depend on the heat-treatment
parameters. The investigation was focused on the abra-
sive wear resistance under different contact conditions as
well as on the direct correlations between the mechanical
properties and the wear resistance, obtained by using a
multifunctional, circumferentially notched and fatigue
pre-cracked tensile bar (CNPTB) specimen.
8,9
2 EXPERIMENTAL PART
2.1 Material
The material, used in this research was AISI
H11-type hot-work tool steel with a reduced content of
silicon (< 0.3 %) and the chemical composition pre-
sented in Table 1. The material was produced by SIJ
Metal Ravne, Slovenia and was delivered in the forged
and soft-annealed state, which was then used to machine
the CNPTB specimens (Figure 1). Ten specimens were
prepared for each heat-treatment group and a fatigue
pre-crack of about 0.5 mm was produced by rotat-
ing-bending loading in the V-notch root. More details are
provided in Ref.
8
Table 1: Hot-work tool steel’s chemical composition in w/%
Element C Si Mn Cr Mo V
Content 0.36 0.22 0.25 5.02 1.25 0.43
2.2 Heat treatment
After fatigue pre-cracking the specimens were heat
treated in an Ipsen VTTC-324-R horizontal vacuum fur-
nace with high-pressure quenching in nitrogen gas at
1.05 bar. After two-step preheating to 850 °C at a heating
speed of 10 °C/min, the specimens were finally heated to
two different austenitizing temperatures of 990 °C and
1030 °C. After 20 min of holding time at the austenit-
izing temperature the specimens were rapidly cooled to
80 °C (l
800–500
= 0.9), followed by two-stage tempering.
8
All the specimens underwent primary 2h tempering at
540 °C, while secondary tempering was performed at 6
different temperatures (550 °C, 570 °C, 590 °C, 600 °C,
G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
352 Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358
Table 2: Heat-treatment groups
Group A
T A
= 990 °C/20 min
Group B
T
A
= 1030 °C/20 min
T
T1
= 540 °C/2h
A1 T
T2
= 550 °C/2h B1 T
T2
= 550 °C/2h
A2 T T2 = 570 °C/2h B2 T T2 = 570 °C/2h
A3 T T2
= 590 °C/2h B3 T
T2
= 590 °C/2h
A4 T T2
= 600 °C/2h B4 T
T2
= 600 °C/2h
A5 T T2
= 610 °C/2h B5 T
T2
= 610 °C/2h
A6 T T2
= 630 °C/2h B6 T
T2
= 630 °C/2h
Figure 1: CNPTB master specimen and extracted specimens

610 °C and 630 °C), resulting in 12 different heat-treat-
ment groups (Table 2).
2.3 Mechanical properties
For each heat-treatment group five different mechani-
cal properties were measured, including the fracture
toughness, hardness, compressive and bending strengths,
and the strain-hardening exponent. Fracture toughness
was determined by subjecting the CNPTB specimen to
tensile loading at a cross-head speed of 1.0 mm/min until
fracture. By measuring the load at fracture the size of the
brittle fractured area fracture toughness can then be cal-
culated using Equation 1.
6
After fracturing the CNPTB
specimen according to ASTM E1820-18
10
the hardness
was measured circumferentially on both fractured parts
(2 × 3 measurements) using the Rockwell C method, ac-
cording to the ISO 6508-1:2016 standard.
10
Afterwards,
one part of the fractured CNPTB specimen was used to
cut 1 8×8m mdisc for wear testing and 1 0×1 2m m
cylinder for compressive strength measurement, per-
formed according to the ASTM E9 standard
11
and
strain-hardening exponent determined from the slope of
the logarithmic form of the true-stress vs. true-strain
curve within the plastic region.
12
From another part
 5 × 60 mm rod was machined for a 4-point bending
test, according to ASTM E290-14.
13
2.4 Tribological testing
Tribological testing was focused on the abrasive wear
resistance, simulated by a pin-on-disc reciprocating-slid-
ing-contact configuration and an Al
2
O
3
ball (1750 HV)
used as an oscillating counter-body. Thus, all the wear
(abrasive wear) was focused on the tool-steel disc speci-
men. Tests were performed at room temperature under
dry-sliding conditions. For each heat-treatment group
four different contact conditions were applied. First and
second configurations, denoted K1 and K2, involved a
frequency of 1 Hz (v
s
= 0.01 m/s), a testing time of
7500 s (s = 60 m) and normal loads of 16 N and 40 N,
corresponding to the nominal contact pressures of
800 MPa and 1100 MPa. For the third and fourth config-
urations (K3 and K4), the main difference is in the fre-
quency and sliding speed applied. The frequency was in-
creased to 15 Hz, corresponding to a sliding speed of
0.12 m/s and a testing time reduced to 830 seconds (s =
100 m). The test parameters are given in Table 3.
Table 3: Tribological test parameters
K1 K2 K3 K4
Hertz contact pressure
(MPa)
800 1100 800 1100
Normal load (N) 16 40 16 40
Sliding speed (m/s) 0.01 0.01 0.12 0.12
Frequency (Hz) 1 1 15 15
Test time (s) 7500 7500 830 830
Sliding distance (m) 60 60 100 100
3 RESULTS AND DISCUSSION
3.1 Mechanical properties
Table 4 lists all 5 main mechanical properties of the
investigated AISI H11-type hot-work tool steel depend-
ing on the austenitizing and tempering temperatures ap-
plied. The hardness is decreasing with an increased tem-
pering temperature and is increasing with an increased
austenitizing temperature. The values range from
49.3 HRC to 39.8 HRC for the lower austenitizing tem-
perature of 990 °C and from 51.8 HRC to 40.7 HRC for
the higher austenitizing temperature of 1030 °C.
In terms of fracture toughness, the values are increas-
ing with increased austenitizing and tempering tempera-
tures. The fracture toughness values are in the range
30–87 MPa m for the lower austenitizing temperature of
990 °C and from 45 to 115 MPa m for the higher
austenitizing temperature of 1030°C. The highest value
of 114.9 MPa m is obtained at the austenitizing temper-
ature of 1030 °C and tempering temperature of 630 °C.
G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358 353
Table 4: Mechanical properties at different heat-treatment conditions
Group
T
A
(°C)
T
T2
(°C)
Hardness
HRC
Fracture tough-
ness
K
Ic
(MPa m)
Bending strength
s
B (MPa)
Compressive
strength
s
C
(MPa)
Strain-hardening
exponent; n
A1
990
550 49.3 ± 1.0 29.9 ± 1.5 4547 ± 50 1967 ± 17 0.45 ± 0.10
A2 570 48.3 ± 1.8 33.6 ± 1.9 4372 ± 30 1916 ± 29 0.44 ± 0.11
A3 590 47.8 ± 0.5 36.0 ± 3.2 4156 ± 25 1791 ± 67 0.45 ± 0.14
A4 600 46.2 ± 0.8 38.1 ± 2.9 4000 ± 19 1740 ± 19 0.43 ± 0.13
A5 610 44.3 ± 0.7 48.0 ± 4.4 3790 ± 13 1652 ± 29 0.45 ± 0.13
A6 630 39.8 ± 0.6 86.9 ± 3.0 3259 ± 27 1450 ± 19 0.59 ± 0.05
B1
1030
550 51.8 ± 0.2 45.6 ± 4.3 4744 ± 36 2063 ± 15 0.42 ± 0.04
B2 570 49.7 ± 1.3 51.5 ± 6.0 4585 ± 14 2056 ± 13 0.49 ± 0.09
B3 590 47.9 ± 1.2 58.4 ± 5.9 4388 ± 16 1904 ± 18 0.49 ± 0.10
B4 600 47.8 ± 0.8 64.2 ± 9.3 4221 ± 18 1834 ± 19 0.45 ± 0.09
B5 610 46.3 ± 0.5 87.6 ± 11.0 3997 ± 20 1732 ± 14 0.44 ± 0.03
B6 630 40.7 ± 1.4 114.9 ± 2.1 3518 ± 96 1562 ± 24 0.55 ± 0.08

Both the bending and compressive strengths are in-
creasing in accordance with increased hardness, with
higher austenitizing and lower tempering temperatures
resulting in higher strengths. The bending strength is in
the range 3260–4750 MPa and the compressive strength
in the range 1450–2060 MPa (Table 3). From the me-
chanical properties measured only the strain-hardening
exponent (n) is almost independent on the of the heat-
treatment conditions. For both austenitizing temperatures
and tempering temperatures up to 610 °C it shows a con-
stant value of about 0.45. Only at the highest tempering
temperature of 630 °C is the value increased over 0.55
(0.55–0.59), as shown in Table 4.
3.2 Tribological properties
Tribological properties for each heat treatment group,
comprising the average steady-state coefficient of fric-
tion and wear rate (wear volume divided by normal load
and sliding distance; mm
3
/Nm) analysed under four dif-
ferent contact conditions are listed in Table 5.
3.2.1 Coefficient of friction
Figure 2 shows the steady-state coefficient of friction
for the investigated H11-type hot-work tool steel as a
function of tempering temperature and contact condi-
tions for the two applied austenitizing temperatures of
990 °C and 1030 °C. In both cases the coefficient of fric-
tion is more determined by the contact conditions, espe-
cially the load, than the tempering temperature. For
low-load conditions (16 N, 800 MPa; K1 & K3) the
steady-state coefficient of friction is in the range
0.77–0.82 and for high-load conditions (40 N,
1100 MPa; K2 & K4) in the range 0.67–0.78, with a
higher sliding speed (K4) provoking a further drop in
friction. However, in terms of heat-treatment conditions,
the investigated tool steel in general shows a negligible
increasing trend in the coefficient of friction under
dry-sliding abrasive wear conditions with increased
austenitizing and tempering temperatures, with the dif-
ference being less than 5 %.
3.2.2 Wear rate
Wear rates for the investigated H11-type hot-work
tool steel austenitized at two different temperatures are
G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
354 Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358
Table 5: Tribological parameters under different heat-treatment conditions
Group
T A
(°C)
T
T2
(°C)
Coefficient of friction; μ (/) Wear rate; k (×10
–5
mm
3
/Nm)
K1 K2 K3 K4 K1 K2 K3 K4
A1
990
550 0.78 0.73 0.75 0.67 3.30 ± 0.38 2.59 ± 0.87 2.81 ± 0.31 2.97 ± 0.70
A2 570 0.78 0.73 0.80 0.73 3.60 ± 0.16 2.84 ± 0.25 2.27 ± 0.34 1.70 ± 0.26
A3 590 0.79 0.72 0.79 0.70 3.61 ± 0.27 3.02 ± 0.14 2.18 ± 0.26 2.04 ± 0.31
A4 600 0.78 0.72 0.80 0.71 4.11 ± 0.31 3.40 ± 0.27 2.65 ± 0.28 2.98 ± 0.03
A5 610 0.77 0.73 0.84 0.68 3.80 ± 0.96 3.76 ± 0.11 3.17 ± 0.22 2.86 ± 0.82
A6 630 0.78 0.78 0.81 0.69 4.19 ± 0.33 3.53 ± 0.72 3.44 ± 0.39 4.19 ± 0.34
B1
1030
550 0.82 0.78 0.82 0.69 3.45 ± 0.05 2.97 ± 0.04 1.76 ± 0.35 1.75 ± 0.27
B2 570 0.79 0.73 0.85 0.71 4.40 ± 0.36 2.83 ± 0.15 2.48 ± 0.39 1.59 ± 0.27
B3 590 0.79 0.71 0.76 0.71 3.53 ± 0.51 4.28 ± 0.61 1.26 ± 0.11 1.51 ± 0.34
B4 600 0.82 0.74 0.80 0.70 4.61 ± 0.56 4.78 ± 0.97 3.09 ± 0.28 2.12 ± 0.27
B5 610 0.80 0.70 0.80 0.68 5.19 ± 0.27 4.26 ± 0.69 2.33 ± 0.74 3.49 ± 0.05
B6 630 0.80 0.74 0.87 0.71 4.90 ± 0.43 4.34 ± 0.36 3.94 ± 0.41 3.85 ± 0.11
Figure 2: Influence of tempering temperature and contact conditions
on steady-state coefficient of friction for: a) austenitizing temperatures
of 990 °C and b) 1030 °C

shown in Figure 3. In all cases abrasive wear was the
prevailing wear mechanism, accompanied by minor ad-
hesive wear, as exemplified in Figure 4. Furthermore,
for both austenitizing temperatures and all four contact
conditions the wear rate increases with tempering tem-
perature. However, the rate of increase intensifies with
higher austenitizing temperature, which also results in
higher wear rates, especially for low-sliding-speed con-
ditions, as shown in Figure 3. For a lower austenitizing
temperature of 990 °C (Figure 3a) the wear rate under
low-sliding-speed conditions (v
s
= 0.01 m/s; K1 & K2)
ranges between 2.6 and 4.2 × 10
–5
mm
3
/Nm and between
2.0 and 3.5 × 10
–5
mm
3
/Nm under high-sliding-speed
conditions (v
s
= 0.12 m/s; K3 & K4). For a higher
austenitizing temperature of 1030 °C (Figure 3b) the
wear rate under low-sliding-speed conditions (K1 & K2)
is 3.0–5.0 × 10
–5
mm
3
/Nm and under high-sliding-speed
conditions (K3 & K4) 1.2–3.5 × 10
–5
mm
3
/Nm.
3.3. Correlations – coefficient of friction
3.3.1 Friction vs. hardness
The dependence of the coefficient of friction of the
investigated H11-type hot-work tool steel on the hard-
ness obtained by different heat-treatment regimes (Ta-
ble 2) is shown in Figure 5. In general, under dry-sliding
conditions and dominant abrasive wear coefficient of
friction of the investigated tool steel is more-or-less inde-
pendent of the hardness. Only for low-load and high-
sliding-speed conditions (K3), with intensified adhesive
wear component (Figure 4b), is the coefficient of fric-
tion reduced with hardness, although the drop is in the
range of just 5–10 % over the hardness range
39–52 HRC.
3.3.2 Friction vs. fracture toughness
Similarly, as for hardness, the coefficient of friction
of the investigated hot-work tool steel is in general inde-
pendent of the fracture toughness (Figure 6). Again, the
exception is low-load and high-sliding-speed conditions
G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358 355
Figure 3: Influence of tempering temperature and contact conditions
on wear rate for: a) austenitizing temperatures of 990 °C and
b) 1030 °C
Figure 4: Typical wear scars; a) A6, p
H
= 1100 MPa, v
s
= 0.01 m/s;
b) A6, p
H
= 800 MPa, v
s
= 0.12 m/s
Figure 5: Dependence of the investigated hot-work tool steel coeffi-
cient of friction on hardness under dry-sliding contact and different
contact conditions

(K3), with the coefficient of friction showing an increas-
ing trend with a higher fracture toughness.
3.3.3 Friction vs. strength
As expected, the coefficient of friction follows the
same dependency on bending and compressive strength
(Figure 7) as observed for hardness, being independent
of the dry-sliding-contact conditions, promoting abrasive
wear and showing a decreasing trend with increased
strength as the adhesive-wear component starts to domi-
nate.
3.3.4 Friction vs. strain-hardening exponent
In terms of the strain-hardening exponent n (Fig-
ure 8) the coefficient of friction is independent for very
mild, low-load, low-sliding-speed (K1) and very harsh,
high-load, high-sliding-speed (K4) conditions. However,
it increases with n when mixed contact conditions are ap-
plied (high/low; K2 & K3). For low-load, low-sid-
ing-speed conditions (K1) the material is in pure elastic
regime and for high-load, high-sliding-speed conditions
(K4) in the severe plastic regime. On the other hand, in
the K2 and K3 case the elasto-plastic regime takes place
with effective strain-hardening behaviour of the material
in the tribological contact.
3.4 Correlations – Wear rate
3.4.1 Wear rate vs. hardness
Figure 9 represents the correlation between the in-
vestigated AISI H11-type hot-work tool steel dry-slid-
ing-wear resistance and hardness for 4 different contact
conditions. For all contact conditions the abrasive wear
resistance improves with hardness. However, the effect
of hardness on the wear-resistance improvement is more
pronounced for the high sliding speed conditions (K3 &
K4), with the wear rate being reduced by up to 60 %
within the investigated working hardness range
G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
356 Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358
Figure 6: Dependence of the investigated hot-work tool steel coeffi-
cient of friction on fracture toughness under dry-sliding contact and
different contact conditions
Figure 8: Dependence of the investigated hot-work tool steel’s coeffi-
cient of friction on strain-hardening exponent under dry-sliding con-
tact and different contact conditions
Figure 7: Dependence of the investigated hot-work tool steel coeffi-
cient of friction on bending and compressive strength under dry-slid-
ing contact and different contact conditions

(38–52 HRC), as compared to only about 20 % under
low-sliding-speed conditions (K1 & K2).
3.4.2 Wear rate vs. fracture toughness
The dependence of the investigated hot-work tool
steel’s dry-sliding wear resistance on the fracture tough-
ness is shown in Figure 10. In contrast to the hardness,
the increased fracture toughness results in a similar
dry-sliding wear-rate increase, regardless of the sliding
speed and load applied. The increase in the fracture
toughness from 30 MPa√m to 115 MPa√m resulted in
60–70 % higher wear rates, as shown in Figure 10.
3.4.3 Wear rate vs. fracture toughness
Figure 11 shows the dependence of the investigated
hot-work tool steel’s dry-sliding wear rate on the bend-
ing and compressive strengths. In accordance with the
G. PU[ et al.: DRY-SLIDING WEAR RESISTANCE OF AISI H11-TYPE HOT-WORK TOOL STEEL
Materiali in tehnologije / Materials and technology 57 (2023) 4, 351–358 357
Figure 11: Dependence of the investigated hot-work tool steel’s wear
rate on bending and compressive strength under dry sliding contact
and different contact conditions
Figure 9: Dependence of the investigated hot-work tool steel’s wear
rate on the hardness under dry-sliding contact and different contact
conditions
Figure 10: Dependence of the investigated hot-work tool steel’s wear
rate on the fracture toughness under dry-sliding contact and different
contact conditions
Figure 12: Dependence of the investigated hot-work tool steel’s wear
rate on strain-hardening exponent under dry-sliding contact and differ-
ent contact conditions

hardness-strength relationship the wear resistance im-
proves with the bending and compressive strengths in the
same manner as with hardness (see Figure 9). An in-
crease in the bending and compressive strengths of about
50 % provides 20–25 % better dry-sliding wear resis-
tance of the investigated AISI H11-type hot-work tool
steel when operating under low-sliding-speed conditions
and almost 50 % under more severe, high-sliding-speed
conditions, as shown in Figure 11. Those results reveal
the hardness as the dominant property when it comes to
the abrasive wear resistance of hot-work tool steels.
3.4.4 Wear rate vs. strain-hardening exponent
In terms of strain-hardening exponent (Figure 12) the
wear rate under dry-sliding contact conditions increases
with its increase, again high sliding speed conditions re-
sulting in stronger increase rate (60 % vs. 10 %).
4 CONCLUSIONS
Aim of this study was to analyse the tribological
properties of AISI H11-type hot-work tool steel under
different dry-sliding contact conditions with prevailing
abrasive wear and to correlate its friction and wear per-
formance with the mechanical properties, varied by ap-
plying different heat treatments (i.e., austenitizing and
tempering temperature). The main results of the investi-
gation can be summarized in the following conclusions.
By increasing the austenitizing temperature an increase
in all mechanical properties, including hardness, tough-
ness and strength, is obtained. A higher tempering tem-
perature, on the other hand, increases the toughness
while it results in drop in hardness and strength. There-
fore, choosing the proper austenitizing and tempering
temperatures provides optimal combination of tool hard-
ness, strength and toughness. In terms of tribological
properties the coefficient of friction under dry-sliding
contact conditions and abrasive wear was found to be
largely independent of the heat-treatment conditions. It is
more determined by the contact conditions, especially
the load than the austenitizing and tempering tempera-
ture. However, the wear rate increases with higher tem-
pering temperature, while a higher austenitizing temper-
ature intensifies this dependency, especially for
high-sliding-speed conditions. A mechanical-tribological
properties correlation analysis revealed the coefficient of
friction as being more-or-less independent of the me-
chanical properties within the working hardness range
and dominant abrasive wear. However, under low-load,
high-sliding-speed conditions and intensified adhesive
wear component coefficient of friction is reduced by
hardness and strength. Also, the contact conditions pro-
moting material elasto-plastic behaviour in the contact
(low load, high sliding speed, and high load, low sliding
speed) will result in a reduced coefficient of friction with
higher hardness and strength and thus lower toughness
and strain-hardening exponent. An increase in the hard-
ness and strength leads to increased abrasive wear resis-
tance under dry-sliding contact conditions, with im-
provement being more pronounced for high sliding speed
and thus higher contact-temperature conditions. Fracture
toughness has the opposite effect, reducing the abrasive
wear resistance at a similar rate, regardless of the contact
conditions. Therefore, hardness and strength of the mate-
rial are the dominant mechanical properties controlling
abrasive wear resistance of the hot-work tool steel.
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