Carbide glossary: the words on a label, a quote or a datasheet

ANSI C grades: A grade system running from C1 to C8, used alongside the ISO letters P, M and K with a number. See grades and binders.

APT (ammonium paratungstate): The white crystalline powder most tungsten concentrate is processed into, and the main tungsten raw material traded; USGS says its price is the reference for carbide powder too. See price and the tungsten market.

Binder: The metal that holds the carbide grains together, most often cobalt, sometimes nickel or iron. ITIA puts it simply: the carbide gives hardness, the cobalt toughness. See grades and binders.

Binderless WC: Tungsten carbide with no metal binder. It has low fracture resistance and bending strength, which is why binders are added; one commercial binderless material is listed at 2800 HV. See hardness.

Blue oxide: What APT becomes when heated under slightly reducing conditions (oxidising conditions give yellow WO3), and the usual starting material for tungsten metal powder. See how it is made.

Brazed tip: A carbide edge brazed to a steel body. The two shrink differently as the joint cools, leaving residual stress, and the solder must come off before recycling. See carbide drill bits.

Sources: Purdue WHIN course page (Tooling U-SME): carbide grade systems; USGS Open-File Report 2005-1028: tungsten recycling in the US (data year 2000); ITIA: properties of tungsten intermediates; LLNL manuscript on OSTI (2018): cobalt binder in WC composites; OSTI 2376169 (2023): binders in cemented tungsten carbide; ITIA: Applications and markets; Materials review (Dec 2024, PMC11722073): WC hard alloys; OSTI 1922808 (2022): WC-Co and binderless WC; Materials Science Forum 347-349 (2000): residual stress in brazed carbide tools; ITIA: Recycling of tungsten, part 1 (May 2018 newsletter).

Carburization: Heating tungsten metal powder with carbon black at 1,300 to 2,200 °C in hydrogen to make WC powder (ITIA). The hotter the run, the coarser the carbide grain. See tungsten carbide powder.

Cast carbide (fused tungsten carbide): A WC/W2C eutectic, melted, cast and quenched into very hard particles for surface hardening. One 2010 paper puts it at 78 to 82 wt% W2C. See how it is made.

Cemented carbide: Hard carbides, mainly WC, bound in a tough metal such as cobalt, nickel or iron. Hardmetal, sintered carbide and plain carbide are other names for it. See how it is made.

Cermet: A ceramic-metal composite. ISO 513:2012 codes uncoated carbide based on TiC or TiN as HT, the family also called cermets. See grades and binders.

Cobalt leaching: Corrosion in aggressive media that dissolves the cobalt and leaves a skeleton of WC grains (2021 review). Leaching by water-based lubricants is usually blamed for punching-die failures, though a 1997 study found the rate too low to explain them. See grades and binders.

Crater wear: Wear on the tool face, where it runs hotter; it is generally diffusion or solution wear, while flank wear is generally abrasion. See carbide drill bits.

Cubic carbides: TiC, NbC and TaC put in place of some WC. A 2020 review says they raise wear resistance and resistance to plastic deformation. See grades and binders.

CVD (chemical vapor deposition): A hot coating process: the substrate sits at 800 to 1150 °C in thermally activated CVD (2022 review), and the layers are 5 to 20 µm thick (ITIA). See coatings.

Sources: ITIA: properties of tungsten intermediates; The Paton Welding Journal 2010, no. 4: cast tungsten carbide powders; ITIA: Cemented carbides, a success story (June 2010 newsletter); ITIA: Applications and markets; NTP Report on Carcinogens, 13th edition: cobalt-tungsten carbide profile; USGS Mineral Commodity Summaries 2026: tungsten; ISO 513:2012 preview text: classification of hard cutting materials; Materials (2021, PMC8538869): corrosion of cemented carbides; Corrosion 53, no. 10 (1997): cobalt leaching of WC-Co punching dies; AASTMT course IM212 (2017): tool wear and tool life; Materials (2019, PMC6747969): wear of uncoated carbide turning Ti-6Al-4V; Rizzo et al., Materials 2020 (PMC7142786): cutting-tool materials review; Materials review (2022, PMC9415707): coatings for cutting tools.

Density: Measured for carbide by water displacement under ASTM B311. ASTM warns that density alone cannot evaluate a grade, since two ingredients can offset each other. Try the weight check.

EDM (electrical discharge machining): Cutting with sparks that melt and vaporize conductive material. It works on carbide because WC-Co conducts electricity; the re-solidified skin it leaves is the white layer. See electricity and heat.

End mill: A milling cutter. ITIA describes carbide rod ground into drills and end mills, with the final shape ground by diamond tools after sintering. See carbide vs HSS.

Eta phase: A brittle cobalt-tungsten-carbon phase that can form in the substrate when hot CVD coating anneals a WC-Co tool. See coatings.

Fisher number: The average particle size from the ASTM B330 air-permeability test. ASTM says it is a relative value for process control, not an absolute size. See tungsten carbide powder.

Flank wear: A wear land rubbed into the tool by the new cut surface, and the usual measure of tool life; a paper citing ISO 3685:1993 gives VBB = 0.3 mm (average land width) or VBBmax = 0.6 mm (maximum width) as the most commonly used end-of-life limits in tool-life tests with sintered carbide tools. See carbide drill bits.

Grade: A carbide's recipe. ITIA names WC grain size and cobalt content as the two main parameters for adjusting hardness and toughness. See grades and binders.

Grain growth inhibitor: Under 1 wt% of VC, Cr3C2, TaC, NbC, TiC or Mo2C, added to stop WC grains growing during sintering; VC and Cr3C2 work best (2021 paper). See grades and binders.

Grain size: The mean WC grain size. ISO 4499-2:2008 recommends these terms, each measured by the mean-linear-intercept method. See grades and binders.

Green part: A pressed part before sintering, held by paraffin or a similar agent and easy to machine (NTP); some are presintered at 500 to 800 °C first to strengthen them. See how it is made.

Sources: ASTM B311-22: density of cemented carbides; Micromachines (2024, PMC11205691): EDM white layer; Materials (Dec 2024, PMC11676650): EDM of WC-6Co; ITIA: Recycling of tungsten, part 1 (May 2018 newsletter); ITIA: Cemented carbides, a success story (June 2010 newsletter); OSTI 2324591 (2023): coated carbide milling tools; ASTM B330-20: Fisher number by air permeability; AASTMT course IM212 (2017): tool wear and tool life; Materials Science Forum vol. 986 (University of Mons copy): ISO 3685 wear limits; ITIA: properties of tungsten intermediates; Materials (2021, PMC8004746): grain growth inhibitors in WC-Co; ISO 4499-2:2008 preview text: WC grain size terms; NTP background document on hard metals (2010).

Hard scrap: Solid pieces, which USGS lists as cemented carbide parts, off-spec alloy parts and excess from casting, pressing or forging. Used inserts are the plainest example. See sell tungsten carbide.

Hard-metal lung disease: A giant-cell interstitial pneumonia, which can turn into lung fibrosis, that NTP ties to cobalt-tungsten carbide and not to cobalt alone. See dust and safety.

Hardfacing: Welding a hard, wear-resistant alloy onto a metal wearing surface, as a 1943 US government guide defines it; tungsten hardfacing is also sprayed or infiltrated onto steel and drill-bit cutters. See coatings.

HIP and sinter-HIP: HIP presses a sintered part with hot gas, up to 400 MPa and 2,000 °C per a 2021 paper. Sinter-HIP ends the sintering cycle by raising gas pressure, up to 10 MPa in a 2020 paper's account; ITIA calls pressure-aided sintering a standard technology for defect-free carbide. See how it is made.

HSS (high-speed steel): A tool steel with 1.5 to 20% tungsten that can be hardened up to HRC 63-68 and keeps most of its hardness to about 550 °C (ITIA). A university lecture sums it up as high toughness but low hot hardness. See carbide vs HSS.

HVOF (high-velocity oxy-fuel): A thermal spray that fires softened powder through a supersonic flame to make a dense coating. The US Navy chose HVOF WC-17Co as its alternative to hard chrome plating. See coatings.

Sources: USGS Open-File Report 2005-1028: tungsten recycling in the US (data year 2000); USGS Open-File Report 01-349: tantalum recycling (1998 data); NTP Report on Carcinogens, 13th edition: cobalt-tungsten carbide profile; US Government Printing Office (1943): hard surfacing guide; Int. J. Refractory Metals and Hard Materials 98 (2021), open access: tungsten recycling; Annales de Chimie - Science des Materiaux 45(3), 2021: HIP of cemented carbide; Annales de Chimie - Science des Materiaux 44(4), 2020: sintering of WC-Co; ITIA: Cemented carbides, a success story (June 2010 newsletter); ITIA: Tungsten in steel (December 2008 newsletter); ITIA: Tungsten in steel (2008 newsletter, 2024 file); King Saud University course slides: cutting-tool materials; SERDP/ESTCP project WP-200023 (completed 2006): HVOF coatings; NASA NTRS 20130009937 (2008): Navy HVOF WC-Co landing gear coating.

Insert (indexable insert): A replaceable carbide tip screwed onto a steel holder for turning, milling, grooving, threading or drilling. ITIA says inserts are typically above 80% tungsten. See where it is used.

ISO 513 groups: The ISO 513:2012 work groups: P blue steel, M yellow austenitic stainless, K red cast iron, N green non-ferrous, S brown heat-resistant alloys and titanium, H grey hardened steel. Lower numbers favour wear resistance, higher ones toughness. See grades and binders.

ISO 513 material codes: The letter codes for the cutting material: HW for uncoated WC carbide of 1 µm grain or more, HF below 1 µm, HT for TiC or TiN based, HC for coated. See grades and binders.

K1C (fracture toughness): Resistance to a growing crack, in MPa·m½. In ITIA's example, a 6% cobalt grade at 1450 HV10 gives 12 and a 20% cobalt grade at 800 HV10 gives 25. The Palmqvist test is the most accepted method, but a 2024 review says it becomes invalid above about 14 MPa·m½ as measured by chevron-notched bending. See hardness.

Macrocrystalline WC: Coarse WC made straight from ore concentrate by the thermit, or macro, process. USGS says it goes into hardfacing, diamond tool matrices and, once milled, mining tool tips. See how it is made.

Metric ton unit (mtu): A unit of tungsten trioxide content; USGS says one mtu of tungsten trioxide holds 7.93 kg of tungsten. See price and the tungsten market.

Mohs hardness: About 9 for tungsten carbide, slightly below diamond, and 5 for cobalt, according to NTP. See hardness.

Sources: ITIA: Recycling of tungsten, part 1 (May 2018 newsletter); ITIA: Cemented carbides, a success story (June 2010 newsletter); ISO 513:2012 preview text: classification of hard cutting materials; Eclética Química 49 (2024): review of cemented carbide properties and tests; USGS Open-File Report 2005-1028: tungsten recycling in the US (data year 2000); USGS Mineral Commodity Summaries 2026: tungsten; NTP background document on hard metals (2010).

PCD and PDC cutters: Polycrystalline diamond sintered onto a tough carbide substrate (ITIA). Sandia describes the PDC cutter as a diamond table on a carbide disc brazed onto the bit body. See where it is used.

PVD (physical vapor deposition): Coating by evaporation, sputtering or ion plating at about 200 to 500 °C (2023 paper), in layers of 2 to 8 µm (ITIA). ITIA says PVD gives the keenest edges. See coatings.

Regrind: Grinding a worn tool sharp again. A tool-wear course says to regrind when average flank wear reaches a set allowable value, to avoid sudden breakdown, and calls regrinding uneconomical once wear enters its third, rapid stage. See carbide drill bits.

Rockwell A (HRA): The Rockwell scale ASTM B294 sets for carbide: a diamond indenter, 60 kgf total force, readings of 80 HRA and up. A UPenn lecture puts carbide at up to 92 HRA. See hardness.

Scheelite: Calcium tungstate (CaWO4), or white ore, one of the only two commercially important tungsten minerals, USGS says. See how it is made.

Sintering: The furnace step, at 1,350 to 1,550 °C per NTP, that turns pressed powder into dense carbide. ITIA says the part shrinks 17 to 24% laterally but keeps its shape. See how it is made.

Soft scrap: Fine scrap: grinding sludge, loose powder, swarf, turnings and dust, in the USGS list. ITIA says most of it is recycled chemically. See sell tungsten carbide.

Straight grade: A grade of WC and cobalt only; ITIA gives 90% WC and 10% cobalt as the typical example. See grades and binders.

Swarf: Chips and turnings from machining, in USGS usage, and a kind of soft scrap. See sell tungsten carbide.

Sources: Sandia report SAND2024-13076 (2024): PDC drill bits; ITIA: Cemented carbides, a success story (June 2010 newsletter); OSTI 2324591 (2023): coated carbide milling tools; AASTMT course IM212 (2017): tool wear and tool life; ASTM B294-17: Rockwell A hardness of cemented carbides; University of Pennsylvania IPD 501 lecture: speeds and feeds; USGS Open-File Report 2005-1028: tungsten recycling in the US (data year 2000); NTP background document on hard metals (2010); ITIA: Recycling of tungsten, part 2 (August 2019 newsletter); ITIA: Applications and markets; USGS Circular 1196-Y (2010): titanium recycling.

Transverse rupture strength (TRS): The strength figure ASTM B406 uses to judge carbide grade powders by their sintered strength. ASTM says it is not a design value. See hardness.

Tungsten heavy alloy: Not carbide but tungsten metal bound with nickel-iron or nickel-copper, 80 to 98 wt% tungsten, with sintered pieces typically 16 to 18 g/cm³. See tungsten vs tungsten carbide.

Vickers hardness (HV): Resistance to a diamond indenter, usually read as HV30 for carbide. ITIA spans cemented carbide grades from about 800 to 2800 HV10. See hardness.

W2C: The tungsten-rich carbide, two tungsten atoms to each carbon, and the larger share of cast carbide. See how it is made.

WC (tungsten carbide): Tungsten monocarbide, 6.13 wt% carbon when stoichiometric, with a density of 15.6 g/cm³ in the NTP table and 15.68 g/cm³ at 298 K in NIST's database. See tungsten vs tungsten carbide.

Wolframite: Black ore, a series of iron- and manganese-rich tungstates, (Fe,Mn)WO4, and the other commercial tungsten mineral. See how it is made.

Zinc process: A direct recycling route: molten zinc bloats the binder of sorted, clean hard scrap and is distilled off, leaving powder of the same composition. ITIA's 2019 newsletter put it at about a third of hard scrap in Europe and the US. See price and the tungsten market.

Every carbide form in this glossary still holds its tungsten, from a brazed saw tip to grinding sludge. We buy carbide in any form and pay the shipping: send the forms, a rough weight and photos through the quote form, or read how to sell tungsten carbide.

Sources: ASTM B406-96(R21): transverse rupture strength of cemented carbides; Materials (2021, PMC8037632): tungsten heavy alloys; Materials (2020, PMC7288021): tungsten heavy alloy work pieces; NTP background document on hard metals (2010); Eclética Química 49 (2024): review of cemented carbide properties and tests; ITIA: Cemented carbides, a success story (June 2010 newsletter); The Paton Welding Journal 2010, no. 4: cast tungsten carbide powders; ITIA: properties of tungsten intermediates; NTP Report on Carcinogens, 13th edition: cobalt-tungsten carbide profile; NIST ceramics data portal: tungsten carbide (Reeber and Wang, 1999); USGS Open-File Report 2005-1028: tungsten recycling in the US (data year 2000); ITIA: Recycling of tungsten, part 2 (August 2019 newsletter); USGS Open-File Report 01-349: tantalum recycling (1998 data).