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How it comparesCarbide vs HSS: how the two tool materials compare
In carbide vs HSS, each material wins on different ground: cemented carbide is harder, stiffer and keeps its hardness much hotter, so it cuts faster, while high-speed steel (HSS) is tougher and cheaper. This page gives the sourced numbers, how to tell the two apart, and why they go in separate bags when you sell your scrap.
What is the difference between carbide and HSS?
High-speed steel (HSS) is a tool steel: an iron base alloyed with tungsten, molybdenum, chromium and vanadium, then hardened by heat treatment. Cemented carbide is not a steel. It is grains of tungsten carbide (WC), a hard compound of tungsten and carbon, held in a metal binder, most often cobalt.
HSS gets its hardness in the furnace: ITIA, the International Tungsten Industry Association, describes heating it close to melting, quenching it and tempering it at 550-600 °C. Carbide gets it from WC grains, 1 to 2 microns across in the two grades ITIA pictures, milled with cobalt, shaped and sintered, the heating step that turns a porous pressed part into a dense solid.
- T1, the original HSS: 18.0% tungsten, 4.1% chromium, 1.1% vanadium and 0.75% carbon (ITIA).
- M2, which superseded T1 (University of Pennsylvania lecture, UPenn): 6.0% tungsten, 5.0% molybdenum, 4.2% chromium and 2.0% vanadium.
- M42, a cobalt HSS (UPenn): 9.2% molybdenum and 1.4% tungsten in ITIA's table.
- Carbide: most grades hold 50 to 97% WC and 3 to 16% cobalt, says the National Toxicology Program (NTP); 90% WC with 10% cobalt is a typical straight grade (ITIA).
HSS holds 1.5 to 20% tungsten across its grades (ITIA), while carbide inserts typically carry more than 80%. A carbide grade is one recipe of grain size and cobalt content (see carbide grades).
Sources: ITIA, Tungsten in Steel (December 2008 newsletter); ITIA, Tungsten in Steel, grade table (2008 newsletter, file of 2024); ITIA, Cemented carbides: a success story (June 2010); ITIA, Applications and markets; ITIA, Properties of tungsten and its intermediates; ITIA, Recycling of tungsten, part 1 (2018); NTP, cobalt-tungsten carbide background document (2010); University of Pennsylvania, IPD 501 Speeds and Feeds lecture.
Carbide vs high speed steel: the numbers side by side
Carbide wins on hardness, heat, stiffness and speed; HSS wins on toughness and tool price. More cobalt or coarser grains make a carbide grade tougher and softer. UWI is a 2020 University of the West Indies paper with one table for both; KSU (King Saud University) and AAST (Arab Academy) are course notes.
| Property | High-speed steel | Cemented carbide |
|---|---|---|
| Hardness | HRC 63-68 (ITIA); 68-70 HRC for cobalt HSS (UPenn) | Up to 92 HRA, about 80 HRC (UPenn) |
| Hot hardness | Keeps most of it to about 550 °C (ITIA); usable up to a 600-650 °C contact temperature at about 60 HRC, per sources cited in a 2021 review | High hardness over a wide range of temperatures (KSU) |
| UWI hardness table: room temperature, 540 °C, 760 °C | 85-87, 77-82, very low | 89-94, 80-87, 70-82 |
| Toughness | High (UPenn, KSU) | Poor (UPenn); brittle (ASTM B406) |
| Transverse rupture strength (UWI) | 3,800-4,500 MPa | 1,400-2,400 MPa |
| Stiffness | 1020 and 4340 steel: 205 GPa (MIT) | 561-585 GPa at 10-12% cobalt (OSTI) |
| Density | 1020 and 4340 steel: 7.8 g/cm³ (MIT); no HSS figure in these sources | 13.1 g/cm³ at about 19% cobalt (ORNL) to 15.2 g/cm³ for NTP's K01 grade; some steel-cutting P grades are lighter |
| Cutting speed | Baseline; cobalt HSS about 10% faster (UPenn) | 2 times HSS (UPenn) to about 4 times (UWI) |
| Taylor exponent n | 0.08-0.20 (AAST) | 0.20-0.50 (AAST) |
| Grinding | Regrind when average flank wear reaches the allowed value, the general rule for cutting tools (AAST) | Same regrind rule (AAST); the shape itself is ground with diamond tools after sintering (ITIA) |
| Tool cost | Low (UPenn); a four-flute quarter-inch HSS end mill cost $11 to $45, by base material and coating, at a DOE plant in 2005 | High (UPenn) |
Compare hardness down a column, not across: HRC, HRA and the UWI table's unnamed scale differ. ASTM B406 treats rupture strength as a powder-quality check, not a design value.
Sources: ITIA, Tungsten in Steel (December 2008 newsletter); ITIA, Cemented carbides: a success story (June 2010); University of Pennsylvania, IPD 501 Speeds and Feeds lecture; University of the West Indies, IConETech-2020 paper on coated cutting tools; King Saud University, cutting tool materials lecture; Materials (Basel) 2021, 14(24):7779, high-speed steel review; ASTM B406-96(R21), transverse rupture strength of cemented carbides; MIT 3.11 Mechanics of Materials, metals property table (1999); OSTI 1981641, properties of four commercial WC-Co grades (2022); OSTI 1607097, ORNL binder-jet WC-Co part (2019); NTP, cobalt-tungsten carbide background document (2010); AASTMT course IM212, Tool Wear and Tool Life (2017); DOE Kansas City Plant, Evaluation of End Mill Coatings (2005).
Why carbide cuts two to four times faster
Carbide cuts faster because it stays hard when the cut gets hot. UPenn's rule of thumb is twice the surface speed (SFM, surface feet per minute) of plain HSS, and the UWI paper says about four times.
HSS keeps most of its hardness only to about 550 °C (ITIA), yet a 2021 Frontiers paper says the hottest point of the tool/chip interface may reach 600 to 1000 °C.
The Taylor equation, VTn = C, turns that into tool life. V is cutting speed (m/min), T is tool life (min), and n and C are constants for one tool and work pair. Take n = 0.125 for HSS and 0.25 for carbide, inside the AAST ranges in the table. A 10% rise in speed then cuts HSS tool life by about 53% (1 - 1/1.18) and carbide tool life by about 32% (1 - 1/1.14).
A 2021 aluminum drilling paper says carbide is used for rapid hole drilling because it outlasts HSS and is harder, with a better finish and longer life, especially dry. See tungsten carbide drill bits.
Sources: University of Pennsylvania, IPD 501 Speeds and Feeds lecture; University of the West Indies, IConETech-2020 paper on coated cutting tools; ITIA, Tungsten in Steel (December 2008 newsletter); Frontiers in Materials 2021, oxidation of cemented carbides; Karandikar et al., Precision Engineering 2013, Taylor tool life; AASTMT course IM212, Tool Wear and Tool Life (2017); Materials (Basel) 2021, drilling Al6061-T651.
Where HSS is still the right tool
HSS earns its place where toughness, a forgiving setup or a low tool price matter more than speed. In the 2018 global tool market, carbides held half and HSS came next (2020 review).
- Short runs. A 2005 Department of Energy (DOE) plant study of end mills in 304 stainless found that "Most milling operations do not need a micrograin carbide end mill with a multi-layer coating to complete a small production run." In a number of cases, it adds, that tool is not worn out and its tooling cost per part is high.
- Setups that flex. The same report says that carbide tool needs very high cutting speeds and rigid tooling that prevents deflection, and pays off when run as designed on large lots.
- Cuts that knock the edge. UPenn rates HSS high in toughness and carbide poor, which is what to weigh on an interrupted cut. Heat is not the issue there: one 2020 study of a 5% cobalt carbide grade turning steel calculated average tool temperatures 16% lower at 120 m/min and 15% lower at 180 m/min for interrupted than for continuous cutting.
Sources: Materials (Basel) 2020, 13(6):1377, cutting tool review; DOE Kansas City Plant, Evaluation of End Mill Coatings (2005); University of Pennsylvania, IPD 501 Speeds and Feeds lecture; Materials (Basel) 2020, hot hardness of cemented carbides.
How to tell a carbide tool from an HSS one
Start with weight. WC-cobalt grades run from about 13.1 g/cm³ at 19% cobalt (ORNL) to 15.2 g/cm³ for the K01 grade in NTP's table. Steels such as 1020 and 4340 are listed at 7.8 g/cm³ (MIT). None of these sources measures HSS itself, so no HSS figure is printed here, but HSS is a steel.
That makes a solid carbide drill about 1.7 to 1.95 times as heavy as the same drill in plain steel (13.1 and 15.2 against 7.8), in line with UPenn's 1.5 to 2 times. Compare it with a known HSS drill of the same size, or run the water test on tungsten carbide density.
- Light grades. NTP's table puts the P grades, made for cutting steel, at 8.5 to 13.4 g/cm³, so a light insert is not proof of steel.
- Tipped tools. Carbide is joined to steel by brazing or welding (ITIA), so weigh only solid pieces this way.
- Color. WC is gray (NTP), but TiN coating is gold (ITIA) and HSS end mills come coated too (DOE).
- Magnet. Cobalt is ferromagnetic (USGS), and a lab measured 0.5 T magnetic saturation on a WC-Co part with about 19% cobalt, so a pull on the magnet does not prove steel.
USGS also lists the spark pattern from grinding the metal on an abrasive wheel. Skip that test: NTP says grinding hard metal makes dust carrying cobalt and tungsten carbide (is tungsten carbide toxic).
Sources: OSTI 1607097, ORNL binder-jet WC-Co part (2019); NTP, cobalt-tungsten carbide background document (2010); MIT 3.11 Mechanics of Materials, metals property table (1999); University of Pennsylvania, IPD 501 Speeds and Feeds lecture; ITIA, Cemented carbides: a success story (June 2010); DOE Kansas City Plant, Evaluation of End Mill Coatings (2005); USGS Circular 1196-A-M (2004), metal sorting and cobalt; NTP, Report on Carcinogens profile, cobalt-tungsten carbide.
Keeping HSS out of a carbide lot
Keep HSS in its own container, since it comes in carbide's shapes: ITIA says about 95% of HSS goes into machining tools such as drills, taps, milling cutters and saw blades.
USGS says the zinc process for hard scrap such as used inserts is not a purification process, so careful sorting and pretreatment are essential; ITIA says most unsorted hard scrap goes to chemical conversion.
- One container for carbide and one for HSS and other steel at each machine.
- Brazed and tipped tools in a bag of their own.
- Every bag labeled with what it holds.
Worn and broken carbide still holds its tungsten. Send photos and a rough weight through the quote form, and mention any HSS bag there. We pay the shipping from anywhere in the US and pick up in every city in California, Arizona and Nevada; see selling tungsten carbide.
Sources: ITIA, Tungsten in Steel (December 2008 newsletter); USGS Open-File Report 01-349, tantalum recycling in the US in 1998; ITIA, Recycling of tungsten, part 2 (2019).
Questions people ask
Is carbide better than HSS?
For speed and wear life, yes, on a rigid machine and a long run. HSS is tougher and cheaper, which suits short runs and cuts that knock the edge.
HSS vs carbide drill bits: which should I use?
Carbide for rapid hole drilling, where it outlasts HSS and is harder. HSS for a short run or a setup that flexes, since a DOE end mill study found carbide pays off only with rigid tooling, high speeds and large lots. See carbide drill bits.
Is HSS the same as tungsten steel?
Often in name: ITIA notes that high-speed steels are often called tungsten steels. Even the richest grade holds far less tungsten than a carbide insert.
Can I put HSS in with my carbide scrap?
Keep them apart, since carbide recycling depends on careful sorting. Bag HSS separately and say what each bag holds when you ask for a quote.
Keep reading
Carbide drill bits
Solid carbide, carbide tipped, and what wears them out
Hardness
How hard it is, how it is measured, and the toughness it trades for it
Density and the weight check
Weigh and measure a piece, and see whether it reads like carbide
Tungsten vs tungsten carbide
A metal and a ceramic compound, and how to tell them apart
Have tungsten carbide to sell?
Tell us what form it is in and about how much it weighs, and add a few photos. Ship it from any state and we pay the shipping, or we pick up anywhere in California, Arizona and Nevada.