Steel X75WCrV18-4-1 QT64-66
Hardness band
EN X75WCrV18-4-1 · GB W18Cr4V
QT64-66 = qT 64–66 HRC
Maximum hardness and red hardness for wear-critical tooling; lowest toughness, use only for compressive-loaded parts.
Values for the QT64-66 condition
Other X75WCrV18-4-1 tempers and conditions
X75WCrV18-4-1 is listed in 7 conditions; see the grade overview at X75WCrV18-4-1.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
QT 60–62 HRC | Preferred bearing condition: slightly lower austenitizing temperature plus sub-zero and stabilizing tempers for maximum dimensional stability and toughness at 500 °C service. | — | — | — | 61 HRC | 20 W/m·K |
QT 62–64 HRC | General-purpose hardened condition balancing hot hardness and toughness for high-temperature bearings and cutting tools. | — | — | — | 63 HRC | 20 W/m·K |
ADefault Solution annealed | Standard stock condition for machining rings, blanks and tools before hardening. | 560 | 900 | 12 | 23 HRC | 22 W/m·K |
Stress relieved | Intermediate step for large rings to prevent distortion during subsequent hardening. | 570 | 910 | 12 | 24 HRC | 3.3 % IACS |
Cold drawn, annealed | Choose for small-diameter bar with close tolerance and good surface prior to hardening. | 700 | 980 | 8 | 26 HRC | 3.3 % IACS |
Hardened + tempered + surface nitrided / oxy-nitrided | Adds a 1000–1200 HV diffusion case for extra galling and adhesive-wear resistance on cages, tools and races. | 1,850 | 2,100 | 1 | 63 HRC | 3.1 % IACS |
QT64-66This page QT 64–66 HRC | Maximum hardness and red hardness for wear-critical tooling; lowest toughness, use only for compressive-loaded parts. | 2,000 | 2,200 | 0.5 | 65 HRC | 3 % IACS |
What is X75WCrV18-4-1 QT64-66?
X75WCrV18-4-1 QT64-66 is X75WCrV18-4-1 heat treated to QT64-66 — maximum hardness and red hardness for wear-critical tooling; lowest toughness, use only for compressive-loaded parts. X75WCrV18-4-1 QT64-66 has a yield strength of 2,000 MPa (290 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Elongation at break is 0.5% and the elastic modulus is 220 GPa (31.9 Msi). X75WCrV18-4-1 QT64-66 has a density of 8.7 g/cm³ (0.314 lb/in³), heavier than 99% of steel grades. It melts at 1,250°C (2,282 °F). A is the default condition FabDigit quotes; QT64-66 is available on request or by drawing note.
Advantages
- High strength — 2,000 MPa (290 ksi), better than 100% of steel grades
- High service temperature — 600°C (1,112 °F), better than 98% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 0.5%, worse than 100% of steel grades
- Difficult to machine — 5/100, worse than 100% of steel grades
- Difficult to weld — 5/100, worse than 100% of steel grades
- Limited formability — 2/100, worse than 100% of steel grades
- High embodied carbon — 4.2 kg CO₂/kg, worse than 95% of steel grades
X75WCrV18-4-1 QT64-66 properties
Typical room-temperature values for X75WCrV18-4-1 QT64-66; 21 are specific to this condition. Other listed values are X75WCrV18-4-1 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
X75WCrV18-4-1 QT64-66 has a density of 8.7 g/cm³ (0.314 lb/in³), heavier than 99% of steel grades. It melts at 1,250°C (2,282 °F).
Mechanical14
X75WCrV18-4-1 QT64-66 has a yield strength of 2,000 MPa (290 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Elongation at break is 0.5% and the elastic modulus is 220 GPa (31.9 Msi).
Thermal6
X75WCrV18-4-1 QT64-66 is rated for continuous service to 600°C (1,112 °F). It conducts heat at 24 W/m·K (13.9 BTU/hr·ft·°F), worse than 90% of steel grades. Thermal expansion is 11 µm/m·K (6.11 µin/in·°F).
Electrical3
X75WCrV18-4-1 QT64-66 conducts electricity at 3 % IACS, worse than 91% of steel grades.
Chemical & Environmental2
Corrosion resistance is poor (18/100), better than 83% of steel grades.
Sustainability4
Producing a kilogram of X75WCrV18-4-1 QT64-66 takes about 58 MJ of energy and emits 4.2 kg of CO₂ — more than 95% of steel grades. Typical recycled content is 30%.
Manufacturability8
X75WCrV18-4-1 QT64-66's machinability is not recommended (5/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with X75WCrV18-4-1 QT64-66
Is X75WCrV18-4-1 easy to machine?
Machine only in the annealed state (≤269 HB) with rigid setups, cobalt-HSS or coated carbide, low speed and heavy feed; after hardening the part must be ground with friable Al₂O₃ or CBN wheels and ample coolant to avoid grinding burn.
Can X75WCrV18-4-1 be welded?
Not a structural weldable steel — repair welding only with matching HSS filler, 500–550 °C preheat/interpass, immediate temper at 560 °C; otherwise cracking is nearly certain.
Can X75WCrV18-4-1 be formed, bent or molded?
Hot forge 1100–900 °C with slow, uniform heating (pre-heat 850 °C) and immediate slow furnace cooling to anneal; cold forming is not feasible.
What surface finishes work on X75WCrV18-4-1?
Not anodizable; protect with oil, phosphate or black oxide, or apply nitriding/steam-oxide/PVD TiN-TiAlN. Hardened surfaces lap and superfinish to bearing-grade Ra <0.05 µm.
X75WCrV18-4-1 chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| Cbearing version of T1 held to a narrow carbon band | 0.7 – 0.8 | 0.75 |
| Si | 0.1 – 0.45 | 0.3 |
| Mn | 0.1 – 0.4 | 0.3 |
| P | ≤ 0.03 | — |
| Smax; ≤0.015 for aerospace bearing quality | ≤ 0.03 | — |
| Cr | 3.8 – 4.5 | 4.15 |
| Wprimary red-hardness element | 17.2 – 18.7 | 18 |
| V | 1 – 1.25 | 1.1 |
| Moresidual/optional | ≤ 0.6 | 0.3 |
| Coresidual | ≤ 0.5 | — |
| Fe | balance | — |
X75WCrV18-4-1 QT64-66 — frequently asked
What is X75WCrV18-4-1 QT64-66 used for?
X75WCrV18-4-1 QT64-66 is typically used for high-temperature rolling bearings, jet engine and turbine bearing components and hot-working bearing applications. In short: T1-type bearing steel; best hot hardness here; 400 °C service capability.
What is the yield strength of X75WCrV18-4-1 QT64-66?
X75WCrV18-4-1 QT64-66 has a typical yield strength of 2,000 MPa (290 ksi) and a tensile strength of 2,200 MPa (319 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is X75WCrV18-4-1 QT64-66 easy to machine?
Not especially — machinability is rated not recommended (5/100, worse than 100% of steel grades). Machine only in the annealed state (≤269 HB) with rigid setups, cobalt-HSS or coated carbide, low speed and heavy feed; after hardening the part must be ground with friable Al₂O₃ or CBN wheels and ample coolant to avoid grinding burn.
Can X75WCrV18-4-1 QT64-66 be welded?
Not readily — weldability is rated not recommended (5/100). Not a structural weldable steel — repair welding only with matching HSS filler, 500–550 °C preheat/interpass, immediate temper at 560 °C; otherwise cracking is nearly certain.
What surface finishes work on X75WCrV18-4-1 QT64-66?
Not anodizable; protect with oil, phosphate or black oxide, or apply nitriding/steam-oxide/PVD TiN-TiAlN. Hardened surfaces lap and superfinish to bearing-grade Ra <0.05 µm.
Can X75WCrV18-4-1 QT64-66 be formed, bent or molded?
Hot forge 1100–900 °C with slow, uniform heating (pre-heat 850 °C) and immediate slow furnace cooling to anneal; cold forming is not feasible.
What is the maximum service temperature of X75WCrV18-4-1 QT64-66?
X75WCrV18-4-1 QT64-66 is rated for continuous use to about 600°C (1,112 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between X75WCrV18-4-1-A and X75WCrV18-4-1 QT64-66?
A is the default condition — standard stock condition for machining rings, blanks and tools before hardening. QT64-66: maximum hardness and red hardness for wear-critical tooling; lowest toughness, use only for compressive-loaded parts. Yield strength is 560 MPa in A versus 2,000 MPa in QT64-66.
Sources
- EN ISO 4957 — Tool steels — CEN/ISO (2018)
- GB/T 9943 — High speed tool steel bars (W18Cr4V) — SAC (2008)
- ASTM A600 — Tool Steel, High Speed (T1) — ASTM (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- High speed steel HS18-0-1 / T1 datasheet — Böhler / Erasteel (2020)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.