Steel SUP13
GB SUP13
SUP13 is a JIS nickel-chromium spring steel intended for large-diameter, heavily loaded springs that need high toughness and fatigue resistance, supplied hot rolled, annealed, spheroidized, normalized, cold drawn or quenched and tempered to 40–44, 44–48 or 48–52 HRC.
Reference datasheet — SUP13 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 QT 44-48 HRC condition
SUP13 tempers and conditions
SUP13 is supplied in 9 conditions, soft to hard. QT 44-48 HRC is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize Annealed | Softest, most machinable condition — used before heavy cold upsetting or deep machining of torsion-bar ends. | 450 | 740 | 22 | 210 HB | 8 % IACS |
Solution annealed | Pick for machining, cold forming or coiling of heavy sections before hardening. | 500 | 800 | 18 | 230 HB | — |
Normalized | Uniform fine pearlitic structure for stock preparation before hardening, or for lightly loaded parts. | 600 | 960 | 14 | 29 HRC | 7.8 % IACS |
Hot rolled | Mill supply condition for bars and flats that will be formed and then quench-and-tempered by the spring maker. | 620 | 1,000 | 12 | 31 HRC | — |
Cold drawn | Close-tolerance, bright bar or wire for small springs and pins that will be hardened after forming. | 900 | 1,050 | 8 | 33 HRC | 7.5 % IACS |
Q&T 40–44 HRC (oil quenched, high temper) | Tougher, lower-strength spring temper for very thick leaf springs, stabilizer bars and impact-loaded parts. | 1,200 | 1,330 | 11 | 42 HRC | — |
QT 44-48 HRCDefault Q&T 44–48 HRC (standard spring temper) | The standard service condition for SUP13 leaf and heavy coil springs — best balance of fatigue strength and toughness. | 1,420 | 1,570 | 9 | 46 HRC | — |
Q&T 44–48 HRC + shot peened | Standard production route for automotive leaf/coil springs — peening compressive layer raises fatigue life several-fold. | 1,420 | 1,570 | 9 | 47 HRC | 7.2 % IACS |
Q&T 48–52 HRC (high-strength temper) | Maximum stress capability for torsion bars and highly stressed coil springs; accept lower toughness and higher notch/hydrogen sensitivity. | 1,620 | 1,800 | 6 | 50 HRC | — |
What is SUP13?
SUP13 is a JIS nickel-chromium spring steel intended for large-diameter, heavily loaded springs that need high toughness and fatigue resistance, supplied hot rolled, annealed, spheroidized, normalized, cold drawn or quenched and tempered to 40–44, 44–48 or 48–52 HRC. The default QT condition gives 1420 MPa yield, 1570 MPa tensile, 9 % elongation and about 440 HB (46 HRC), with service to 250 °C. Its 0.60 % C content makes it effectively unweldable in the finished state, machinability is the lowest of the JIS spring grades listed (score 12), and there is no corrosion resistance without coating. Use SUP12 for smaller, higher-strength coils. SUP13 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). SUP13 has a yield strength of 1,420 MPa (206 ksi) and a tensile strength of 1,570 MPa (228 ksi) — stronger than 96% of steel grades. Elongation at break is 9% and the elastic modulus is 206 GPa (29.9 Msi).
What is SUP13 used for?
- Heavy coil springs
- Railway suspension springs
- Rail bogie helical springs
- Large-section torsion bars
- Mining and crushing equipment springs
- Off-highway suspension springs
Advantages
- High strength — 1,420 MPa (206 ksi), better than 96% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 12/100, worse than 99% of steel grades
- Limited ductility — 9%, worse than 93% of steel grades
- Limited formability — 12/100, worse than 92% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
- Difficult to weld — 18/100, worse than 87% of steel grades
SUP13 properties
Typical room-temperature values for SUP13-QT 44-48 HRC; bars are the position among steel grades.
Physical3
SUP13 has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
SUP13 has a yield strength of 1,420 MPa (206 ksi) and a tensile strength of 1,570 MPa (228 ksi) — stronger than 96% of steel grades. Elongation at break is 9% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
SUP13 is rated for continuous service to 250°C (482 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12.5 µm/m·K (6.94 µin/in·°F).
Electrical3
SUP13 conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SUP13 takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability7
SUP13's machinability is not recommended (12/100, worse than 99% of steel grades); weldability poor (18/100); formability not recommended (12/100).
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. SUP13 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SUP13
Is SUP13 easy to machine?
Machine in the annealed or spheroidized state (≤260 HB) with rigid setups and coated carbide; at 44–52 HRC only grinding, hard turning with CBN or EDM are practical.
Can SUP13 be welded?
Effectively unweldable in service condition (0.60 %C): if unavoidable, preheat 300–350 °C, low-hydrogen consumables, immediate PWHT/temper — avoid welding on spring-active surfaces.
Can SUP13 be formed, bent or molded?
Hot form or coil at 850–950 °C, or cold form annealed stock; then austenitize ~840–870 °C, oil quench (Mo gives good through-hardening in thick sections) and temper 400–500 °C to target hardness, followed by shot peening.
SUP13 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 |
|---|---|---|
| C | 0.56 – 0.64 | 0.6 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.7 – 1 | 0.85 |
| Cr | 0.7 – 0.9 | 0.8 |
| Mo | 0.25 – 0.35 | 0.3 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Curesidual, max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SUP13?
No natural corrosion resistance — use phosphate + oil, zinc-rich or epoxy paint, or powder coat; if electroplating, bake at 190–200 °C to avoid hydrogen embrittlement, and never grind/decarburize the peened surface.
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
How much does SUP13 cost?
SUP13 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.
SUP13 — frequently asked
What is SUP13 used for?
SUP13 is typically used for heavy coil springs, railway suspension springs, rail bogie helical springs, large-section torsion bars, mining and crushing equipment springs and off-highway suspension springs. In short: deep-hardening spring steel; for large-section springs; high toughness spring grade.
What is the yield strength of SUP13?
SUP13 has a typical yield strength of 1,420 MPa (206 ksi) and a tensile strength of 1,570 MPa (228 ksi) — stronger than 96% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is SUP13 easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Machine in the annealed or spheroidized state (≤260 HB) with rigid setups and coated carbide; at 44–52 HRC only grinding, hard turning with CBN or EDM are practical.
Can SUP13 be welded?
Not readily — weldability is rated poor (18/100). Effectively unweldable in service condition (0.60 %C): if unavoidable, preheat 300–350 °C, low-hydrogen consumables, immediate PWHT/temper — avoid welding on spring-active surfaces.
What surface finishes work on SUP13?
No natural corrosion resistance — use phosphate + oil, zinc-rich or epoxy paint, or powder coat; if electroplating, bake at 190–200 °C to avoid hydrogen embrittlement, and never grind/decarburize the peened surface.
Can SUP13 be formed, bent or molded?
Hot form or coil at 850–950 °C, or cold form annealed stock; then austenitize ~840–870 °C, oil quench (Mo gives good through-hardening in thick sections) and temper 400–500 °C to target hardness, followed by shot peening.
What is the maximum service temperature of SUP13?
SUP13 is rated for continuous use to about 250°C (482 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SUP13 QT 44-48 HRC and SUP13-SA?
QT 44-48 HRC is the default condition — the standard service condition for SUP13 leaf and heavy coil springs — best balance of fatigue strength and toughness. SA: softest, most machinable condition — used before heavy cold upsetting or deep machining of torsion-bar ends. Yield strength is 1,420 MPa in QT 44-48 HRC versus 450 MPa in SA.
How much does SUP13 cost?
SUP13 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 4801 — Spring steels — Japanese Industrial Standards Committee (2011)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys (4161 / Cr-Mo spring steels) — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture (spring steel fatigue and shot peening) — ASM International (1996)
- SAE J404 / J1268 — Chemical compositions and hardenability of alloy steels (4161) — SAE International (2019)
- JIS B 2704 — Helical compression and extension springs, design — JISC (2018)
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.