Steel SUJ2
JIS SUJ2 · AISI/SAE 52100 · EN 100Cr6, 1.3505 · GB GCr15
SUJ2 is the Japanese (JIS G 4805) high-carbon chromium through-hardening bearing steel, essentially identical to GCr15, 100Cr6 and AISI 52100.
Values for the Annealed condition
SUJ2 tempers and conditions
SUJ2 is supplied in 7 conditions, soft to hard. Annealed is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
AnnealedDefault soft, machinable delivery condition | Standard stock condition for bars, tubes and rings that will be machined and then through-hardened. | 420 | 660 | 25 | 192 HB | — |
pearlitic bar/wire | Cheapest mill condition for stock that will be spheroidize annealed before machining. | 600 | 1,000 | 10 | 31 HRC | 7.2 % IACS |
Cold Drawn (annealed + cold drawn bar/wire) | Choose for close-tolerance, bright bar or wire feeding cold-heading and turning operations. | 620 | 790 | 12 | 21 HRC | 7 % IACS |
Hardened + stabilized (extra temper 250–350 °C for dimensional stability) | Use for gauges, spindles and high-temperature bearings that must hold size up to ~200–250 °C, accepting 2–5 HRC lower hardness. | 1,650 | 1,900 | 3.5 | 57 HRC | 6 % IACS |
Tempered ~200–230 °C for slightly higher toughness | Pick when a little more toughness and dimensional stability is wanted at modest hardness loss (shafts, cams, gauge bodies). | 1,750 | 2,050 | 2.5 | 60 HRC | — |
Bainite hardened (isothermal/austempered ~230 °C, 58–61 HRC) | Specified for large or shock-loaded bearing rings needing compressive surface stress, better toughness and lower distortion than martensitic hardening. | 1,800 | 2,100 | 3 | 59 HRC | — |
Quenched and tempered | The functional bearing condition: maximum hardness, wear and rolling-contact fatigue resistance for races, balls and rollers. | 1,900 | 2,280 | 1.5 | 62 HRC | 36 W/m·K |
What is SUJ2?
SUJ2 is the Japanese (JIS G 4805) high-carbon chromium through-hardening bearing steel, essentially identical to GCr15, 100Cr6 and AISI 52100. It is chosen for rolling-element bearings, precision shafts, gauges and dies because a 1 %C–1.5 %Cr composition through-hardens to 60–64 HRC with a fine carbide dispersion giving outstanding contact fatigue life and wear resistance. Its limits are near-zero corrosion resistance, very low toughness and essentially no weldability in the hardened state, and a service ceiling of about 120–150 °C set by the low tempering temperature and dimensional stability. SUJ2 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). SUJ2 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 53% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
What is SUJ2 used for?
- Ball bearing rings and balls
- Roller bearings and rollers
- Precision shafts and spindles
- Linear guide rails
- Cam followers
- Gauges and measuring blocks
- Cold work dies
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
- Ductile — tolerates forming and impact — 25%, better than 77% of steel grades
Limitations
- Difficult to weld — 12/100, worse than 96% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
SUJ2 properties
Typical room-temperature values for SUJ2-Annealed; bars are the position among steel grades.
Physical3
SUJ2 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 has a yield strength of 420 MPa (60.9 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 53% of steel grades. Elongation at break is 25% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
SUJ2 is rated for continuous service to 200°C (392 °F). It conducts heat at 46 W/m·K (26.6 BTU/hr·ft·°F), better than 71% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
SUJ2 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 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability8
SUJ2's machinability is fair (45/100, worse than 65% of steel grades); weldability not recommended (12/100); formability fair (35/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. SUJ2 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SUJ2
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.
Manufacturability
The process limits FabDigit applies to SUJ2. Every SUJ2 part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Fair45 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Not Recommend35 / 100 |
|---|---|
| Weldability | Poor12 / 100 |
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 |
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.
Surface treatments FabDigit runs on steel parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel SUJ2 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
How much does SUJ2 cost?
SUJ2 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
SUJ2 — frequently asked
What is SUJ2 used for?
SUJ2 is typically used for ball bearing rings and balls, roller bearings and rollers, precision shafts and spindles, linear guide rails, cam followers and gauges and measuring blocks. In short: premium bearing tool steel.
What is the yield strength of SUJ2?
SUJ2 has a typical yield strength of 420 MPa (60.9 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 53% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SUJ2 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine only in the spheroidize-annealed state (≈40 % of AISI 1212) with rigid setups and carbide tooling; hardened 60+ HRC parts require grinding, honing or CBN hard turning.
Can SUJ2 be welded?
Not readily — weldability is rated not recommended (12/100). Essentially not weldable — high carbon equivalent causes quench cracking; if unavoidable, preheat 300–400 °C and post-weld temper immediately.
What surface finishes work on SUJ2?
No anodizing; protect with oil, phosphate, black oxide or thin hard chrome/nickel plating (bake to avoid hydrogen embrittlement), and superfinish raceways for low friction.
Can SUJ2 be formed, bent or molded?
Cold heading and ring rolling are done from spheroidized stock; hot work 1050–850 °C followed by slow cooling and spheroidize annealing to avoid carbide network.
What is the maximum service temperature of SUJ2?
SUJ2 is rated for continuous use to about 200°C (392 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does SUJ2 cost?
SUJ2 is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in SUJ2?
Yes — SUJ2 is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.