Steel SUJ2 · heat-treated state
Steel SUJ2 Q&T
Properties of the Q&T condition, compared with the other SUJ2 tempers.
The functional bearing condition: maximum hardness, wear and rolling-contact fatigue resistance for races, balls and rollers.
What is SUJ2 Q&T?
SUJ2 Q&T is SUJ2 heat treated to Q&T — the functional bearing condition: maximum hardness, wear and rolling-contact fatigue resistance for races, balls and rollers. SUJ2 Q&T has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,280 MPa (331 ksi) — stronger than 100% of steel grades. Elongation at break is 1.5% and the elastic modulus is 210 GPa (30.5 Msi). SUJ2 Q&T has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,425°C (2,597 °F). Annealed is the default condition FabDigit quotes; Q&T is available on request or by drawing note.
Advantages
- High strength — 1,900 MPa (276 ksi), better than 100% of steel grades
- Polishes to a fine finish — 90/100, better than 100% of steel grades
Limitations
- Limited service temperature — 120°C (248 °F), worse than 100% of steel grades
- Difficult to machine — 8/100, 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
- Limited ductility — 1.5%, worse than 99% of steel grades
SUJ2 Q&T properties
Typical room-temperature values for SUJ2 Q&T — 18 properties are specific to this condition; the rest are grade-level values shared by every SUJ2 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
SUJ2 Q&T has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical15
SUJ2 Q&T has a yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,280 MPa (331 ksi) — stronger than 100% of steel grades. Elongation at break is 1.5% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
SUJ2 Q&T is rated for continuous service to 120°C (248 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 72% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
SUJ2 Q&T conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SUJ2 Q&T takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 55% of steel grades. Typical recycled content is 30%.
Manufacturability8
SUJ2 Q&T's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (5/100); formability not recommended (2/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other SUJ2 tempers and conditions
SUJ2 is also supplied in 6 other conditions. The full side-by-side table is on the SUJ2 overview.
- AnnealedDefaultStandard stock condition for bars, tubes and rings that will be machined and then through-hardened.420 MPa yield · 192 HB
- Q&TThe functional bearing condition: maximum hardness, wear and rolling-contact fatigue resistance for races, balls and rollers.1,900 MPa yield · 62 HRC
- Bainite HardenedSpecified for large or shock-loaded bearing rings needing compressive surface stress, better toughness and lower distortion than martensitic hardening.1,800 MPa yield · 59 HRC
- Q&T 58-62 HRCPick when a little more toughness and dimensional stability is wanted at modest hardness loss (shafts, cams, gauge bodies).1,750 MPa yield · 60 HRC
- Stress RelievedUse for gauges, spindles and high-temperature bearings that must hold size up to ~200–250 °C, accepting 2–5 HRC lower hardness.1,650 MPa yield · 57 HRC
Working with SUJ2 Q&T
Is SUJ2 easy to machine?
Machine only in the spheroidize-annealed state (≈40 % of AISI 1212) with rigid setups and carbide tooling; hardened 60+ HRC parts require grinding, honing or CBN hard turning.
Can SUJ2 be welded?
Essentially not weldable — high carbon equivalent causes quench cracking; if unavoidable, preheat 300–400 °C and post-weld temper immediately.
Can SUJ2 be formed, bent or molded?
Cold heading and ring rolling are done from spheroidized stock; hot work 1050–850 °C followed by slow cooling and spheroidize annealing to avoid carbide network.
What surface finishes work on SUJ2?
No anodizing; protect with oil, phosphate, black oxide or thin hard chrome/nickel plating (bake to avoid hydrogen embrittlement), and superfinish raceways for low friction.
SUJ2 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 |
|---|---|---|
| CJIS G 4805 SUJ2 | 0.95 – 1.1 | 1 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | ≤ 0.5 | 0.35 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Cr | 1.3 – 1.6 | 1.45 |
| Ni | ≤ 0.25 | — |
| Cu | ≤ 0.25 | — |
| Mo | ≤ 0.08 | — |
| Otypical clean-steel oxygen limit for bearing quality | ≤ 0 | — |
| Fe | balance | — |
SUJ2 Q&T — frequently asked
What is SUJ2 Q&T used for?
SUJ2 Q&T is typically used for ball bearing rings and balls, roller bearings and rollers, precision shafts and spindles, linear guide rails, cam followers and gauges and measuring blocks. In short: premium bearing tool steel.
What is the yield strength of SUJ2 Q&T?
SUJ2 Q&T has a typical yield strength of 1,900 MPa (276 ksi) and a tensile strength of 2,280 MPa (331 ksi) — stronger than 100% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SUJ2 Q&T easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine only in the spheroidize-annealed state (≈40 % of AISI 1212) with rigid setups and carbide tooling; hardened 60+ HRC parts require grinding, honing or CBN hard turning.
Can SUJ2 Q&T be welded?
Not readily — weldability is rated not recommended (5/100). Essentially not weldable — high carbon equivalent causes quench cracking; if unavoidable, preheat 300–400 °C and post-weld temper immediately.
What surface finishes work on SUJ2 Q&T?
No anodizing; protect with oil, phosphate, black oxide or thin hard chrome/nickel plating (bake to avoid hydrogen embrittlement), and superfinish raceways for low friction.
Can SUJ2 Q&T be formed, bent or molded?
Cold heading and ring rolling are done from spheroidized stock; hot work 1050–850 °C followed by slow cooling and spheroidize annealing to avoid carbide network.
What is the maximum service temperature of SUJ2 Q&T?
SUJ2 Q&T is rated for continuous use to about 120°C (248 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in SUJ2 Q&T?
Yes — SUJ2 Q&T is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- JIS G 4805 High carbon chromium bearing steels — JISC (2019)
- GB/T 18254 High-carbon chromium bearing steel — SAC (2016)
- ASTM A295 Standard Specification for High-Carbon Anti-Friction Bearing Steel — ASTM (2020)
- EN ISO 683-17 (100Cr6) Heat-treatable steels — ball and roller bearing steels — ISO (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- 100Cr6 / SUJ2 bearing steel datasheet — Ovako / Böhler (2022)
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.