Steel S25C
JIS S25C
S25C is a Japanese medium-carbon machine-structural steel (0.25–0.60 % C band, nominally about 0.25 % C) similar to SAE 1025.
Reference datasheet — S25C 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 N condition
S25C tempers and conditions
S25C is supplied in 6 conditions, soft to hard. N is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — choose for deep cold forming, heavy upsetting or when maximum dimensional stability before final heat treatment is needed. | 240 | 420 | 33 | 116 HB | — |
Hot rolled | Cheapest stock condition for weldments and non-critical machined parts where scale and looser tolerances are acceptable. | 250 | 440 | 28 | 121 HB | — |
NDefault Normalized | Standard JIS G4051 delivery condition — uniform fine grain, predictable strength/toughness for shafts and general machined parts. | 290 | 470 | 30 | 131 HB | — |
Quenched and tempered | Use on small sections (<25 mm) where somewhat higher yield with good toughness is wanted; poor hardenability limits benefit in thick parts. | 380 | 560 | 25 | 170 HB | — |
Carburized & hardened | Choose when a wear-resistant hard skin over a tough, moderately strong core is required (pins, small gears, bushings). | 400 | 600 | 18 | 58 HRC | 10.2 % IACS |
Cold drawn | Pick for close tolerance, bright surface and higher yield strength on turned/CNC parts; residual stress can cause distortion on unbalanced machining. | 420 | 510 | 15 | 148 HB | — |
What is S25C?
S25C is a Japanese medium-carbon machine-structural steel (0.25–0.60 % C band, nominally about 0.25 % C) similar to SAE 1025. Engineers use it for moderately stressed shafts, gears and fasteners, with hot-rolled, normalized, annealed and cold-drawn bar plus quenched-and-tempered and carburized conditions on file. Typical values are 290 MPa yield, 470 MPa tensile and 30 % elongation at 131 HB, with service to 400 °C, a weldability score of 85 and a formability score of 70. Response to quench and temper is limited by the low carbon level, and there is no corrosion resistance; move to S35C or a higher-carbon grade when more hardened strength is needed. S25C has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F). S25C has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 88% of steel grades. Elongation at break is 30% and the elastic modulus is 205 GPa (29.7 Msi).
What is S25C used for?
- shafts
- gears
- fasteners
- machine parts
Advantages
- Ductile — tolerates forming and impact — 30%, better than 93% of steel grades
- Conducts heat well — 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades
- Low embodied carbon — 1.9 kg CO₂/kg, better than 92% of steel grades
- High electrical conductivity — 10.7 % IACS, better than 91% of steel grades
- Easy to machine — 62/100, better than 89% of steel grades
Limitations
- Low strength — 290 MPa (42.1 ksi), worse than 88% of steel grades
S25C properties
Typical room-temperature values for S25C-N; bars are the position among steel grades.
Physical3
S25C has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,425°C (2,597 °F).
Mechanical16
S25C has a yield strength of 290 MPa (42.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 88% of steel grades. Elongation at break is 30% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
S25C is rated for continuous service to 400°C (752 °F). It conducts heat at 51 W/m·K (29.5 BTU/hr·ft·°F), better than 92% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
S25C conducts electricity at 10.7 % IACS, better than 91% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of S25C takes about 25 MJ of energy and emits 1.9 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
S25C's machinability is good (62/100, better than 89% of steel grades); weldability excellent (85/100); formability very good (70/100).
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. S25C is highlighted; hover a dot for its name, or open the interactive family chart.
Working with S25C
Is S25C easy to machine?
Machines easily at ~65 % of 1212; normalized or cold-drawn stock cuts cleaner than annealed, which tends to smear — use positive-rake carbide and adequate feed to avoid built-up edge.
Can S25C be welded?
Readily weldable by SMAW/GMAW/GTAW with E70/ER70S-6 filler; preheat 100–150 °C only for sections above ~25 mm or restrained joints, and re-normalize if carburized parts are welded.
Can S25C be formed, bent or molded?
Good cold bending and upsetting in annealed/normalized condition (bend radius ≈ 1–1.5 t); hot forming 1100–1250 °C followed by normalizing restores grain size.
S25C 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 G4051 S25C | 0.22 – 0.28 | 0.25 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | |
| S | ≤ 0.04 | |
| Curesidual, max | ≤ 0.3 | |
| Niresidual, max | ≤ 0.2 | |
| Crresidual, max; Ni+Cr ≤ 0.35 | ≤ 0.2 | |
| Fe | balance |
What surface finishes work on S25C?
No natural corrosion protection — specify zinc/zinc-nickel plating, manganese phosphate, black oxide plus oil, or paint; surfaces take a good ground/turned finish but only a moderate mirror polish.
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 S25C in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Other
- 1025
How much does S25C cost?
S25C 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.
S25C — frequently asked
What is S25C used for?
S25C is typically used for shafts, gears, fasteners and machine parts. In short: weldable medium-carbon steel; balanced strength and forming; low-cost structural bar stock.
What is the yield strength of S25C?
S25C has a typical yield strength of 290 MPa (42.1 ksi) and a tensile strength of 470 MPa (68.2 ksi) — weaker than 88% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is S25C easy to machine?
Reasonably — machinability is rated good (62/100, better than 89% of steel grades). Machines easily at ~65 % of 1212; normalized or cold-drawn stock cuts cleaner than annealed, which tends to smear — use positive-rake carbide and adequate feed to avoid built-up edge.
Can S25C be welded?
Yes — weldability is rated excellent (85/100). Readily weldable by SMAW/GMAW/GTAW with E70/ER70S-6 filler; preheat 100–150 °C only for sections above ~25 mm or restrained joints, and re-normalize if carburized parts are welded.
What surface finishes work on S25C?
No natural corrosion protection — specify zinc/zinc-nickel plating, manganese phosphate, black oxide plus oil, or paint; surfaces take a good ground/turned finish but only a moderate mirror polish.
Can S25C be formed, bent or molded?
Good cold bending and upsetting in annealed/normalized condition (bend radius ≈ 1–1.5 t); hot forming 1100–1250 °C followed by normalizing restores grain size.
What is the maximum service temperature of S25C?
S25C is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between S25C-N and S25C-CD?
N is the default condition — standard JIS G4051 delivery condition — uniform fine grain, predictable strength/toughness for shafts and general machined parts. CD: pick for close tolerance, bright surface and higher yield strength on turned/CNC parts; residual stress can cause distortion on unbalanced machining. Yield strength is 290 MPa in N versus 420 MPa in CD.
How much does S25C cost?
S25C 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 G4051 — Carbon steels for machine structural use — JSA (2016)
- GB/T 699 — Quality carbon structural steels (25 ) — SAC (2015)
- SAE J403 / ASTM A29 — Carbon steel bars (1025) — SAE / ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings, heat-treat data) — Industrial Press (2020)
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.