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

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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