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
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
Outlet
Inlet
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
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 →
• 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 355 MPa steel 400 HB steel 450 HB steel 500 HB steel
Identification 355MPa 400HB 450HB 500HB
Hardness 180 HV2 405 HV10 475 HV10 560 HV10
Natural rubber
NR
40 shA
PU1
75 shA
PU2
85 shA
PU3
90 shA
Polyurethane, MDI polyether Polyurethane, MDI polyester Polyurethane, TDI polyether
400HB
450HB
500HB
NR
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6 Volume loss [cm3]
Volume loss [cm3]
355MPa
0.5
0.4
PU2
PU3
0.5
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0.0
PU1
0.0 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 Quartz 2/3 mm 0.1/0.6 mm 33% 45° 33% 45°
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 Quartz 2/3 mm 0.1/0.6 mm 33% 45° 33% 45°
Dry-pot wear tester
900
CFB270 Field
CFB300 Dry-pot
CFB300 Field
800
Hardness [HV]
Field test compared to application oriented dry-pot and conventional abrasion tests.
CFB270 Dry-pot
Dry-pot
700 600
500 400 0
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
50 Distance [µm]
100
Field
Up: similar work hardening and deformations Down: dry-pot closer to real application in wear losses
Dry high-stress abrasion tester
Publication: Ojala et al. “Effects of composition and microstructure on the abrasive wear performance of quenched wear resistant steels”, Wear 317 (2014) 225–232
Mechanical behavior 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]
• Strain hardening is a natural defense mechanism of crystalline materials • But it may lead to less ductile behavior on wear surface
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]
Wear surfaces of a quenched steel tested with the different abrasives (slurry-erosion)
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
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:
[email protected] twitter: @Ojala_NJT www.tut.fi/twc/en
