Steel SNCM240-IH (Induction hardened)
Heat-treated state
JIS SNCM240
Specify a quenched-and-tempered core with an induction-hardened 52–58 HRC case for journals, splines and tooth flanks needing wear resistance over a tough core; finish machine before hardening.
Values for the IH condition
Other SNCM240 tempers and conditions
SNCM240 is listed in 10 conditions; see the grade overview at SNCM240.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full anneal, ~815 °C furnace cool | Pick the softest state, fully annealed at about 815 °C with furnace cooling to 187 HB, for rough turning, deep-hole drilling or as an intermediate step before cold forming. | 425 | 700 | 26 | 187 HB | — |
Hot rolled | Choose this untreated as-rolled or as-forged bar (550 MPa yield, 850 MPa tensile, 240 HB) as low-cost stock when you will anneal or quench and temper it yourself. | 550 | 850 | 20 | 22 HRC | 8 % IACS |
~870 °C, air cool | Choose normalising at about 870 °C with air cooling to refine grain and homogenise structure in forgings and rough blanks before quench and temper; 690 MPa yield at 269 HB. | 690 | 930 | 22 | 27 HRC | — |
Cold drawn | Pick annealed-then-cold-drawn small-diameter bar for tight dimensional tolerance and bright surface with direct machining, trading elongation down to 12% for 700 MPa yield. | 700 | 830 | 12 | 22 HRC | 7.8 % IACS |
Q&T to 24–28 HRC | Choose this soft quench-and-temper step, tempered around 620 °C to 24–28 HRC, for large-section shafts, flanges and die shoes where 20% elongation and toughness outrank strength. | 740 | 880 | 20 | 26 HRC | — |
QTDefault Quenched and tempered | Use the standard delivery state, oil quenched near 830 °C and tempered to 255–311 HB, for shafts, gear blanks and connecting rods needing 820 MPa yield with 17% elongation. | 820 | 1,000 | 17 | 30 HRC | — |
IHThis page Induction hardened | Specify a quenched-and-tempered core with an induction-hardened 52–58 HRC case for journals, splines and tooth flanks needing wear resistance over a tough core; finish machine before hardening. | 820 | 1,000 | 15 | 55 HRC | 7.5 % IACS |
Q&T to 28–32 HRC | Pick the 28–32 HRC temper (about 590 °C) as the general-purpose machine-and-use hardness, balancing 850 MPa yield against still-workable cutting behaviour. | 850 | 1,000 | 17 | 30 HRC | 7.8 % IACS |
Q&T to 32–36 HRC | Use tempering near 540 °C to 32–36 HRC for highly loaded shafts, bolts and gear blanks; yield rises to 1000 MPa but cutting resistance increases markedly. | 1,000 | 1,120 | 15 | 34 HRC | — |
Q&T to 38–42 HRC | Choose the 450 °C temper to 38–42 HRC only for small sections such as pins, fasteners and tooling; 1190 MPa yield comes with 12% elongation and poor weldability. | 1,190 | 1,310 | 12 | 40 HRC | — |
What is SNCM240-IH?
SNCM240-IH is SNCM240 heat treated to IH — specify a quenched-and-tempered core with an induction-hardened 52–58 HRC case for journals, splines and tooth flanks needing wear resistance over a tough core; finish machine before hardening. SNCM240-IH has a yield strength of 820 MPa (119 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 87% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi). SNCM240-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). QT is the default condition FabDigit quotes; IH is available on request or by drawing note.
Advantages
- High strength — 820 MPa (119 ksi), better than 87% of steel grades
Limitations
- Difficult to machine — 12/100, worse than 99% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Limited service temperature — 200°C (392 °F), worse than 93% of steel grades
- Low fracture toughness — 45 MPa·√m (41 ksi·√in), worse than 90% of steel grades
SNCM240-IH properties
Typical room-temperature values for SNCM240-IH; 22 are specific to this condition. Other listed values are SNCM240 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SNCM240-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
SNCM240-IH has a yield strength of 820 MPa (119 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 87% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SNCM240-IH is rated for continuous service to 200°C (392 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SNCM240-IH conducts electricity at 7.5 % IACS, worse than 67% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SNCM240-IH takes about 29 MJ of energy and emits 2.3 kg of CO₂ — less than 53% of steel grades. Typical recycled content is 25%.
Manufacturability8
SNCM240-IH's machinability is not recommended (12/100, worse than 99% of steel grades); weldability not recommended (10/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SNCM240-IH
Is SNCM240 easy to machine?
Annealed or quenched-and-tempered material up to about 32 HRC machines efficiently with carbide tooling (roughly 55-65% of AISI 1212). Above 36 HRC switch to CBN or ceramic hard turning, or finish by grinding.
Can SNCM240 be welded?
Carbon equivalent is high (Ceq ≈ 0.75), so welding requires 200-300 °C preheat, low-hydrogen consumables and a post-weld temper. Welding quenched-and-tempered parts degrades heat-affected-zone properties.
Can SNCM240 be formed, bent or molded?
Forge at 1050-1200 °C, finishing no lower than 850 °C, then slow cool or normalize. Cold forming is limited to light bending and upsetting in the annealed condition.
What surface finishes work on SNCM240?
Cannot be anodized; use black oxide, phosphate, zinc or hard chrome plating, or paint for corrosion protection. High-strength parts must be baked at 190 °C or above after plating to remove hydrogen; induction-hardened surfaces can be ground and polished.
SNCM240 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 G 4103 | 0.38 – 0.43 | 0.4 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.7 – 1 | 0.85 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Ni | 0.4 – 0.7 | 0.55 |
| Cr | 0.4 – 0.65 | 0.5 |
| Mo | 0.15 – 0.3 | 0.22 |
| Curesidual, max | ≤ 0.3 | — |
| Fe | balance | — |
SNCM240-IH — frequently asked
What is SNCM240-IH used for?
SNCM240-IH is typically used for carburized gears, shafts and gearbox components. In short: case-hardening Ni-Cr-Mo steel; stronger core than SNCM220; medium-duty carburized gears.
What is the yield strength of SNCM240-IH?
SNCM240-IH has a typical yield strength of 820 MPa (119 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 87% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is SNCM240-IH easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Annealed or quenched-and-tempered material up to about 32 HRC machines efficiently with carbide tooling (roughly 55-65% of AISI 1212). Above 36 HRC switch to CBN or ceramic hard turning, or finish by grinding.
Can SNCM240-IH be welded?
Not readily — weldability is rated not recommended (10/100). Carbon equivalent is high (Ceq ≈ 0.75), so welding requires 200-300 °C preheat, low-hydrogen consumables and a post-weld temper. Welding quenched-and-tempered parts degrades heat-affected-zone properties.
What surface finishes work on SNCM240-IH?
Cannot be anodized; use black oxide, phosphate, zinc or hard chrome plating, or paint for corrosion protection. High-strength parts must be baked at 190 °C or above after plating to remove hydrogen; induction-hardened surfaces can be ground and polished.
Can SNCM240-IH be formed, bent or molded?
Forge at 1050-1200 °C, finishing no lower than 850 °C, then slow cool or normalize. Cold forming is limited to light bending and upsetting in the annealed condition.
What is the maximum service temperature of SNCM240-IH?
SNCM240-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 SNCM240-QT and SNCM240-HR?
QT is the default condition — use the standard delivery state, oil quenched near 830 °C and tempered to 255–311 HB, for shafts, gear blanks and connecting rods needing 820 MPa yield with 17% elongation. HR: choose this untreated as-rolled or as-forged bar (550 MPa yield, 850 MPa tensile, 240 HB) as low-cost stock when you will anneal or quench and temper it yourself. Yield strength is 820 MPa in QT versus 550 MPa in HR.
Sources
- JIS G 4103 Nickel-chromium-molybdenum steels — JSA (2021)
- SAE J404 Chemical Compositions of SAE Alloy Steels (8640) — SAE International (2021)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4: Heat Treating — ASM International (1991)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
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.