Steel SUJ3-A (Solution annealed)
Temper · default condition
JIS SUJ3
The condition bearing bar and tube are normally bought in: soft, uniform spheroidal carbides, ready for turning and subsequent hardening.
Values for the A condition
Other SUJ3 tempers and conditions
SUJ3 is listed in 8 conditions; see the grade overview at SUJ3.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
ADefaultThis page 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-A?
SUJ3-A is SUJ3 in the A temper — the condition bearing bar and tube are normally bought in: soft, uniform spheroidal carbides, ready for turning and subsequent hardening. SUJ3-A 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). SUJ3-A 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).
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-A properties
Typical room-temperature values for SUJ3-A; 14 are specific to this condition. Other listed values are SUJ3 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SUJ3-A 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-A 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-A 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-A 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-A 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-A'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. Confirm any required mill or lot documentation when quoting.
Working with SUJ3-A
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.
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.
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 | — |
SUJ3-A — frequently asked
What is SUJ3-A used for?
SUJ3-A 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-A?
SUJ3-A 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-A 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-A 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-A?
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-A 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-A?
SUJ3-A 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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.