edge effect in high speed slurry erosion wear tests of steels and elastomers
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Edge effect in high speed
slurry erosion wear tests of
steels and elastomers
Niko Ojala1*, Kati Valtonen1, Jussi Minkkinen2 and Veli-Tapani Kuokkala1
1Tampere University of Technology, Department of Materials Science,
Tampere Wear Center, Tampere, Finland 2SSAB Europe Oy, Hämeenlinna, Finland
*email: niko.ojala@tut.fi
Mining
Dredging
Pumping
Pipelines
TanksCrushing
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 erosion wearInlet
Outlet
Overview to topics
1) Materials and methods
2) Results
3) Conclusions
FIMECC BSA PROGRAM
Materials
Steels 400HB 500HB Elastomers NR PU
Hardness [HV10] 414 ± 4 554 ± 2 Hardness [ShA] 40 75
Yield strength [N/mm2] 1000 1250 Tensile strength [N/mm2] 25 23
Tensile strength [N/mm2] 1250 1600 Density [g/cm3] 1.04 1.05
A5 [%] 10 8 Isocyanate type - MDI
Density [g/cm3] 7.85 7.85 Polyol type - polyether
C [max%] 0.23 0.3
Si [max%] 0.8 0.8
Mn [max%] 1.7 1.7
P [max%] 0.025 0.025
S [max%] 0.015 0.015
Cr [max%] 1.5 1
Ni [max%] 1 1
Mo [max%] 0.5 0.5
B [max%] 0.005 0.005
High speed slurry-pot
• Plate samples with and without edge wear
• Two sample angles, two abrasives
– 8/10 and 0.1/0.6 mm natural abrasives with
9 and 33 wt% slurry concentrations, respectively
– 1500 rpm (i.e. 15 m/s at sample tip)
– 4 x 5 minutes (+ 4 x 15 minutes with 45°)
“Wear performance of quenched wear resistant steels in
abrasive slurry erosion” – Wear 354-355(2016)
First part of the study. Without edge protection, and with several sized abrasives.
Wear resistant
steels
Large abrasives
Abrasiveerosion
Elastomer linings
Small abrasives
Mild erosion
Hardness benef its
Def ormations
Consistent perf ormance
Hardness disbenef its
Elasticity
Big dif f erence in perf ormance
Materials
selection
in slurry
erosion
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0
100
200
300
400
500
Granite8/10 mm 9%
90°
Quartz0.1/0.6 mm33% 90°
Granite8/10 mm 9%
45°
Quartz0.1/0.6 mm
33% 45°
Wear
rate
[cm
3/m
2∙h
] 400HB
500HB
NR
PU
EP 400HB
EP 500HB
EP NR
EP PU
Edge effect
• Wear ratio 0.4 to 16 for elastomers, 1.8 to 5 for steels
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0.4 – 0.8
1610
1.8 5
0%
20%
40%
60%
80%
100%
0.01 0.1 1 10
Granite 8/10 mm 9% 45
60 min 20 min Initial
0%
20%
40%
60%
80%
100%
0.01 0.1 1
Sieve size [mm]
Quartz 0.1/0.6 mm 33% 45
Abrasive comminution
• Different abrasive types and sizes are crushed differently
• High- vs low-stress wear – traditional classification
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Wear surfaces,
after 20 minutes,
of 400HB steel
tested with the
different sized
abrasives
Without edge
protection
Change in abrasive embedment
with longer test duration for steels
(a) (b)
(c) (d)
8/10 mm granite
0.1/0.6 mm quartz
500HB steel with
edge protection
After 20 minutes After 80 minutes
For elastomers longer test
duration increased emdebment
Embedded
abrasives
PU with 8/10 mm granite,
80 minutes
NR with 0.1/0.6 mm quartz,
80 minutes
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Embedment of the abrasives…
• In the previous study it was noted that the
abrasives tend to ’fill’ the surface of the
elastomers
X-ray CT image of NR (published in Wear article) FIMECC BSA PROGRAM
…was tried to compensate with
the direct volume measurements
• Alicona 3D-profilometer was experimented
• Results supported that the embedment decreases weight
loss of the elastomers clearly more than with the steels
• As the full confidence
was not reached, the
measurements were
not included
in the paper
High- and low-stress wear of steels
A better classification
Shear band
8/10 mm granite,
80 minutes
0.1/0.6 mm quartz,
80 minutes
400HB steel 500HB steel
Conclusions
• Steels behave much more consistently than elastomers
• Elastomers having an advantage in low-stress conditions
• Edge effect larger with larger abrasives
– About 2x for steels and about 5x for elastomers
• A clear transition from low-stress to high-stress abrasive
erosion was observed
• Indications of ductile to brittle transition on wear surfaces were
observed
– Same has been observed in dry abrasion too with similar steels
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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
www.tut.fi/twc/en
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