Surface degradation mechanisms of cemented carbide drill buttons in iron ore rock drilling

• The wear behavior of cemented carbide rock drill buttons is influenced by many factors, which include the composition and microstructure of the cemented carbide material, the nature of the rock material, and the conditions of the rock drilling operation. Depending on the type of rock and on the drilling procedure used, the cemented carbide is exposed to substantially differing mechanical and thermal conditions. In the present study, the surface degradation and wear mechanisms of cemented carbide drill buttons exposed to iron ore rock drilling have been characterized based on a combination of high resolution scanning electron microscopy (SEM), focused ion beam cross-sectioning (FIB), energy-dispersive X-ray spectroscopy (EDS) and electron back scatter diffraction (EBSD).The results show a significant difference in surface degradation and wear between the front and peripheral buttons of the drill bits. While the front buttons display a relatively smooth worn surface with shallow surface craters the peripheral buttons display a reptile skin pattern, i.e. plateaus, 200-300. μm in diameter, separated by valleys, typically 40-50. μm wide and 15-30. μm deep, The reptile skin pattern is obtained in regions where the peripheral buttons are in sliding contact against the drill hole walls and exposed to high surface temperatures caused by the frictional heating. The results indicate that the reptile skin pattern is related to friction induced thermal stresses rather than mechanical contact stresses, i.e. the reptile skin pattern is formed due to thermal fatigue, rather than mechanical fatigue, caused by the cyclic frictional heating generated at the cemented carbide button/iron ore interface.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Materialteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering (hsv//eng)

Keyword

Cemented carbide

Iron ore

Reptile skin

Rock drilling

Wear mechanisms

Atmospheric temperature

Carbide tools

Carbides

Degradation

Drills

Energy dispersive spectroscopy

Fasteners

Friction

Ion beams

Iron

Iron ores

Ores

Photodegradation

Rock drills

Rocks

Scanning electron microscopy

Stresses

Tribology

Wear of materials

X ray spectroscopy

Cemented carbides

Electron back scatter diffraction

Energy dispersive X ray spectroscopy

High-resolution scanning electron microscopies

Mechanical contact

Surface degradation

Surface temperatures

Steel Forming and Surface Engineering

Stålformning och ytteknik

Publication and Content Type

ref (subject category)

art (subject category)