Steel C25-IH (Induction hardened)
Heat-treated state
EN C25
Selected when only local wear resistance is needed on shaft journals; maximum attainable case hardness is limited by the 0.25 % C content.
Values for the IH condition
Other C25 tempers and conditions
C25 is listed in 6 conditions; see the grade overview at C25.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Choose for maximum ductility before heavy cold forming, deep drawing or cold heading. | 220 | 400 | 32 | 111 HB | — |
Hot rolled | Cheapest mill condition for weldments and non-critical structural parts; scale and looser tolerances. | 225 | 400 | 25 | 116 HB | — |
+NDefault Normalized | Standard stocked condition — uniform fine grain, balanced strength/toughness for shafts, pins and forgings. | 265 | 440 | 30 | 126 HB | — |
IHThis page Induction hardened | Selected when only local wear resistance is needed on shaft journals; maximum attainable case hardness is limited by the 0.25 % C content. | 265 | 440 | 24 | 42 HRC | 9.5 % IACS |
Cold drawn | Pick for close tolerance, bright surface and higher yield strength on automatic-lathe parts; lower ductility and residual stress. | 390 | 470 | 15 | 137 HB | — |
Quenched and tempered | Use for small-section pins and bolts needing higher yield; hardenability is low so benefit disappears above ~25 mm diameter. | 410 | 610 | 22 | 12 HRC | — |
What is C25-IH?
C25-IH is C25 heat treated to IH — selected when only local wear resistance is needed on shaft journals; maximum attainable case hardness is limited by the 0.25 % C content. C25-IH has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 92% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi). C25-IH 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). +N is the default condition FabDigit quotes; IH is available on request or by drawing note.
Advantages
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 9.5 % IACS, better than 75% of steel grades
Limitations
- Limited formability — 10/100, worse than 95% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Difficult to machine — 25/100, worse than 93% of steel grades
- Low strength — 265 MPa (38.4 ksi), worse than 92% of steel grades
- Low fracture toughness — 55 MPa·√m (50.1 ksi·√in), worse than 82% of steel grades
C25-IH properties
Typical room-temperature values for C25-IH; 22 are specific to this condition. Other listed values are C25 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
C25-IH 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
C25-IH has a yield strength of 265 MPa (38.4 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 92% of steel grades. Elongation at break is 24% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
C25-IH is rated for continuous service to 200°C (392 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.9 µm/m·K (6.61 µin/in·°F).
Electrical3
C25-IH conducts electricity at 9.5 % IACS, better than 75% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of C25-IH takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 28%.
Manufacturability8
C25-IH's machinability is poor (25/100, worse than 93% of steel grades); weldability fair (50/100); formability not recommended (10/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with C25-IH
Is C25 easy to machine?
Free-machining-free grade: cold-drawn condition cuts best; normalized bar can be gummy, so use positive-rake carbide, 150–250 m/min and generous coolant to avoid built-up edge.
Can C25 be welded?
Readily welded by SMAW/GMAW/GTAW with E70xx/ER70S-x consumables; CEV ≈ 0.40 so preheat 100–150 °C only for sections over ~25 mm or high restraint.
Can C25 be formed, bent or molded?
Good cold bending and heading in +A/+N condition (bend radius ≈ 1–1.5 t); hot forging 1100–1250 °C followed by normalizing restores grain size.
What surface finishes work on C25?
No anodizing — protect with zinc/zinc-nickel plating, phosphate + oil, black oxide, e-coat or paint; can be case-hardened or induction hardened for wear surfaces.
C25 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 |
|---|---|---|
| CEN 10083-2 C25 / 1.0406 | 0.22 – 0.29 | 0.25 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.7 | 0.55 |
| P | ≤ 0.05 | 0.02 |
| SC25E ≤0.035 S, C25R 0.020–0.040 S | ≤ 0.05 | 0.03 |
| Crresidual | ≤ 0.4 | 0.1 |
| Niresidual | ≤ 0.4 | 0.1 |
| Moresidual; Cr+Mo+Ni ≤ 0.63 | ≤ 0.1 | 0.02 |
| Fe | balance | — |
C25-IH — frequently asked
What is C25-IH used for?
C25-IH is typically used for shafts, pins, forged machine parts and axles. In short: stronger than C22; weldable shaft steel; induction-hardenable carbon grade.
What is the yield strength of C25-IH?
C25-IH has a typical yield strength of 265 MPa (38.4 ksi) and a tensile strength of 440 MPa (63.8 ksi) — weaker than 92% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is C25-IH easy to machine?
Not especially — machinability is rated poor (25/100, worse than 93% of steel grades). Free-machining-free grade: cold-drawn condition cuts best; normalized bar can be gummy, so use positive-rake carbide, 150–250 m/min and generous coolant to avoid built-up edge.
Can C25-IH be welded?
With care — weldability is rated fair (50/100). Readily welded by SMAW/GMAW/GTAW with E70xx/ER70S-x consumables; CEV ≈ 0.40 so preheat 100–150 °C only for sections over ~25 mm or high restraint.
What surface finishes work on C25-IH?
No anodizing — protect with zinc/zinc-nickel plating, phosphate + oil, black oxide, e-coat or paint; can be case-hardened or induction hardened for wear surfaces.
Can C25-IH be formed, bent or molded?
Good cold bending and heading in +A/+N condition (bend radius ≈ 1–1.5 t); hot forging 1100–1250 °C followed by normalizing restores grain size.
What is the maximum service temperature of C25-IH?
C25-IH 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 C25 +N and C25-IH?
+N is the default condition — standard stocked condition — uniform fine grain, balanced strength/toughness for shafts, pins and forgings. IH: selected when only local wear resistance is needed on shaft journals; maximum attainable case hardness is limited by the 0.25 % C content. Yield strength is 265 MPa in +N versus 265 MPa in IH.
Sources
- EN 10083-2 Steels for quenching and tempering — Non-alloy quality steels — CEN (2006)
- JIS G 4051 Carbon steels for machine structural use (S25C) — JISC (2016)
- ASTM A29/A29M — Steel bars, carbon and alloy, hot-wrought (1025) — ASTM (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- Stahlschlüssel / Key to Steel 1.0406 — Verlag Stahlschlüssel (2019)
- Mysteel / SMM — Mysteel (2025)
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.