The document summarizes application oriented wear testing of wear resistant steels conducted for the mining industry. It describes a high speed slurry-pot wear tester that tests steels at speeds up to 20 m/s and with particle sizes up to 10 mm to better simulate mining conditions. Results showed the wear resistant steel's performance decreased with larger particle size and higher impact angles. A dry-pot wear tester and dry abrasion tester also evaluated the steels' mechanical behavior under different wear conditions. The tests revealed hardness alone does not determine wear performance and that ductile to brittle transitions can occur on wear surfaces.

1. Application oriented wear
testing of wear resistant steels
in mining industry
Niko Ojala
Doctoral student
Tampere Wear Center
Tampere University of Technology
Originally presented at
The Nordic Summer Colloquium
on Advanced Steel (NSCAS)
9.8.2015

3. Motivation
In industrial slurry pumping
and in dredging:
• The speeds of the particles
can be up to 30 m/s
(pumps)
• The size of the particles
can vary from micrometers
to several centimeters
• Both above promote
abrasive wear
Inlet
Outlet

4. Contents
• High speed slurry-pot wear tester
• Dry-pot wear tester
• Dry high-stress abrasion tester
• Mechanical behavior of quenched steels in
abrasive wear conditions
• Summary

5. High speed slurry-pot wear
tester
In the published slurry wear studies
• The speeds are often under 10 m/s
(pot testers)
• The particle size is under 1 mm
An application oriented approach:
• The speeds up to 20 m/s
• The particle size up to 10 mm
• High speed slurry-pot wear tester →

6. • Plate samples
• Various test parameters
and materials
Publication:
Ojala, et al., “Wear performance
of quenched wear resistant steels
in abrasive slurry erosion”, Wear,
354-355 (2016) 21-31
Material Identification Hardness
355 MPa steel 355MPa 180 HV2
400 HB steel 400HB 405 HV10
450 HB steel 450HB 475 HV10
500 HB steel 500HB 560 HV10
Natural rubber NR 40 shA
Polyurethane,
MDI polyether
PU1 75 shA
Polyurethane,
MDI polyester
PU2 85 shA
Polyurethane,
TDI polyether
PU3 90 shA

7. 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Granite
8/10 mm
9% 90°
Granite
8/10 mm
9% 45°
Granite
8/10 mm
33% 45°
Granite
2/4 mm
33% 45°
Quartz
2/3 mm
33% 45°
Quartz
0.1/0.6 mm
33% 45°
Volumeloss[cm3]
355MPa 400HB 450HB 500HB
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
Granite
8/10 mm
9% 90°
Granite
8/10 mm
9% 45°
Granite
8/10 mm
33% 45°
Granite
2/4 mm
33% 45°
Quartz
2/3 mm
33% 45°
Quartz
0.1/0.6 mm
33% 45°
Volumeloss[cm3]
NR PU1 PU2 PU3

8. Dry-pot wear tester

9. Field test compared
to application
oriented dry-pot and
conventional
abrasion tests.
Publication:
Vuorinen, Ojala, et al.,
“Erosive and abrasive
wear performance of
carbide free bainitic
steels – comparison of
field and laboratory
experiments”, Tribology
international 98 (2016)
108-115
400
500
600
700
800
900
0 50 100
Hardness[HV]
Distance [µm]
CFB270 Dry-pot CFB270 Field
CFB300 Dry-pot CFB300 Field
Dry-pot
Field
Up: similar work hardening and deformations
Down: dry-pot closer to real application in
wear losses

10. Publication:
Ojala et al. “Effects of composition and microstructure
on the abrasive wear performance of quenched wear
resistant steels”,
Wear 317 (2014) 225–232
Dry high-stress abrasion
tester

11. Two commercial steels from same hardness grade, but two
totally different mechanical behavior on wear surfaces in
dry high-stress abrasion. [Wear 317 (2014) 225–232]
Mechanical behavior

12. Cross-section of a quenched steel sample tested with 8/10 mm granite
slurry at 45° sample angle.
A) SEM BSE image of the plastically deformed surface layer and
B) SEM SE image of a stepwise formed scratch that has cut through the
deformed surface layer.
[Wear, 354-355 (2016) 21-31]
• Strain hardening is a natural defense mechanism of
crystalline materials
• But it may lead to less ductile behavior on wear surface

13. Wear surfaces of a quenched steel tested with the different abrasives (slurry-erosion)

14. Summary
• Application oriented wear testing have proved to
offer added value to simulating demanding
applications in laboratory scale
• Hardness alone doesn’t dictate the wear
performance of quenched wear resistant steels in
demanding conditions (like mining)
• A clear transition from low-stress to high-stress
wear was observed in slurry erosion
• Indications of ductile to brittle transition on wear
surfaces observed both in abrasive slurry as in dry
high-stress abrasion conditions

15. Niko Ojala
Research Scientist, Doctoral student
Tampere University of Technology
Department of Materials Science, Tampere Wear Center
P.O.Box 589, FI-33101 Tampere, Finland
phone: +358 50 317 4516
email: niko.ojala@tut.fi
twitter: @Ojala_NJT
www.tut.fi/twc/en