Steel SUJ3
JIS SUJ3
SUJ3 is the higher silicon/manganese JIS through-hardening bearing steel, giving greater hardenability than SUJ2 and matching GCr15SiMn / 100CrMn6.
Reference datasheet — SUJ3 is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the A condition
SUJ3 tempers and conditions
SUJ3 is supplied in 8 conditions, soft to hard. A is the default FabDigit quotes; the values on this page are for it.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefault Solution annealed | The condition bearing bar and tube are normally bought in: soft, uniform spheroidal carbides, ready for turning and subsequent hardening. | 400 | 660 | 21 | 195 HB | 44 W/m·K |
Hot rolled | As-supplied bar or forging before spheroidising; too hard and carbide-networked for machining, an intermediate state only. | 600 | 980 | 10 | 30 HRC | 8 % IACS |
Cold drawn | Choose for close-tolerance, bright small-diameter bar and rollers where limited stock removal is wanted before hardening. | 640 | 820 | 10 | 24 HRC | 8 % IACS |
Normalized | Used after forging on heavy sections to break up network carbides; always followed by spheroidising, not a delivery condition. | 650 | 1,050 | 9 | 34 HRC | 8 % IACS |
Austempered | Preferred for large railway, rolling-mill and thick-section bearings: compressive surface residual stress, better toughness and less risk of quench cracking than martensitic hardening. | 1,550 | 1,950 | 4 | 59 HRC | — |
Hardened, stabilising temper 240–260 °C | Dimensional-stability (S1-type) temper for bearings running continuously up to about 180 °C, at the cost of a few HRC. | 1,600 | 1,900 | 3 | 58 HRC | — |
Oil hardened, tempered 180–200 °C | Standard bearing temper: slightly lower hardness than QT160 with better toughness and stability to ~150 °C. | 1,700 | 2,050 | 2 | 61 HRC | 35 W/m·K |
Oil hardened, tempered 150–170 °C | Maximum hardness and rolling-contact fatigue life for rings and rollers running below ~120 °C. | 1,800 | 2,200 | 1 | 62 HRC | 34 W/m·K |
What is SUJ3?
SUJ3 is the higher silicon/manganese JIS through-hardening bearing steel, giving greater hardenability than SUJ2 and matching GCr15SiMn / 100CrMn6. It is chosen for larger bearing components supplied as hot-rolled, annealed, normalised or cold-drawn bar, tube and forged rings: 400 MPa yield, 660 MPa tensile, 21 % elongation, about 195 HB (92 HRB) and 44 W/(m·K) in the annealed state. The 1 % C level makes it effectively unweldable, service is capped near 200 °C and there is no corrosion resistance; SUJ2 remains the cheaper choice for thin-walled parts. SUJ3 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,400°C (2,552 °F). SUJ3 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 208 GPa (30.2 Msi).
What is SUJ3 used for?
- Large diameter bearing rings
- Heavy rollers and needle rollers
- Tapered roller bearing cups and cones
- Thrust bearing washers
- Cam followers and track rollers
- Precision spindle bearing components
Advantages
- Polishes to a fine finish — 85/100, better than 99% of steel grades
Limitations
- Difficult to weld — 8/100, worse than 99% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
SUJ3 properties
Typical room-temperature values for SUJ3-A; bars are the position among steel grades.
Physical3
SUJ3 has a density of 7.81 g/cm³ (0.282 lb/in³), lighter than 84% of steel grades. It melts at 1,400°C (2,552 °F).
Mechanical15
SUJ3 has a yield strength of 400 MPa (58 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 60% of steel grades. Elongation at break is 21% and the elastic modulus is 208 GPa (30.2 Msi).
Thermal6
SUJ3 is rated for continuous service to 200°C (392 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical3
SUJ3 conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SUJ3 takes about 31 MJ of energy and emits 2.2 kg of CO₂ — more than 64% of steel grades. Typical recycled content is 30%.
Manufacturability7
SUJ3's machinability is fair (45/100, worse than 65% of steel grades); weldability not recommended (8/100); 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. SUJ3 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SUJ3
Is SUJ3 easy to machine?
Machine only in the spheroidise-annealed state (≈40 % of AISI 1212) with sharp carbide tooling and rigid setups; hardened parts require CBN hard turning or grinding.
Can SUJ3 be welded?
Effectively unweldable — high carbon plus Si/Mn gives quench cracking; if unavoidable, preheat 300–400 °C, use low-hydrogen filler and immediate post-weld temper.
Can SUJ3 be formed, bent or molded?
Hot forge 1050–1150 °C (stop above 850 °C) then normalise and spheroidise; cold ring rolling or upsetting only from the annealed condition, and expect ~0.05 % oil-quench growth to be ground out.
SUJ3 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 |
|---|---|---|
| CGCr15SiMn per GB/T 18254: 0.95–1.05 | 0.95 – 1.1 | 1.02 |
| Siraised vs SUJ2 for hardenability; GCr15SiMn 0.45–0.75 | 0.4 – 0.7 | 0.55 |
| MnGCr15SiMn 0.95–1.25 | 0.9 – 1.15 | 1.02 |
| Crnote: GCr15SiMn specifies 1.40–1.65 Cr, so the two grades are close but not identical | 0.9 – 1.2 | 1.05 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Moresidual max | ≤ 0.08 | |
| Niresidual max | ≤ 0.25 | |
| Curesidual max | ≤ 0.25 | |
| Ototal oxygen, vacuum-degassed bearing quality (typ ≤8 ppm) | ≤ 0 | |
| Fe | balance |
What surface finishes work on SUJ3?
Grind and superfinish to Ra <0.05 µm for raceways; protect with oil, phosphate, black oxide or thin chrome/zinc plating since bare surfaces rust quickly — no anodising.
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).
Organic Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel SUJ3 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- GCr15SiMn
How much does SUJ3 cost?
SUJ3 is a budget-cost steel ($), cheaper than about 90% 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.
SUJ3 — frequently asked
What is SUJ3 used for?
SUJ3 is typically used for large diameter bearing rings, heavy rollers and needle rollers, tapered roller bearing cups and cones, thrust bearing washers, cam followers and track rollers and precision spindle bearing components. In short: deeper-hardening SUJ2; large-bearing JIS grade; finish by grinding only.
What is the yield strength of SUJ3?
SUJ3 has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 660 MPa (95.7 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is SUJ3 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine only in the spheroidise-annealed state (≈40 % of AISI 1212) with sharp carbide tooling and rigid setups; hardened parts require CBN hard turning or grinding.
Can SUJ3 be welded?
Not readily — weldability is rated not recommended (8/100). Effectively unweldable — high carbon plus Si/Mn gives quench cracking; if unavoidable, preheat 300–400 °C, use low-hydrogen filler and immediate post-weld temper.
What surface finishes work on SUJ3?
Grind and superfinish to Ra <0.05 µm for raceways; protect with oil, phosphate, black oxide or thin chrome/zinc plating since bare surfaces rust quickly — no anodising.
Can SUJ3 be formed, bent or molded?
Hot forge 1050–1150 °C (stop above 850 °C) then normalise and spheroidise; cold ring rolling or upsetting only from the annealed condition, and expect ~0.05 % oil-quench growth to be ground out.
What is the maximum service temperature of SUJ3?
SUJ3 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.
What is the difference between SUJ3-A and SUJ3-QT160?
A is the default condition — the condition bearing bar and tube are normally bought in: soft, uniform spheroidal carbides, ready for turning and subsequent hardening. QT160: maximum hardness and rolling-contact fatigue life for rings and rollers running below ~120 °C. Yield strength is 400 MPa in A versus 1,800 MPa in QT160.
How much does SUJ3 cost?
SUJ3 is a budget-cost steel ($), cheaper than about 90% 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.
Sources
- JIS G 4805 High carbon chromium bearing steels — Japanese Standards Association (2019)
- GB/T 18254 High-carbon chromium bearing steel — SAC (China) (2016)
- ISO 683-17 Ball and roller bearing steels — ISO (2014)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys (52100/bearing steels) — ASM International (1990)
- Heat Treater's Guide: Practices and Procedures for Irons and Steels — ASM International (1995)
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.