Steel SNC415 CHT-SP
Finish state
JIS SNC415
CHT-SP = carburized, hardened and shot peened
Pick for highly loaded transmission gears where root bending fatigue governs; peening adds compressive residual stress.
Values for the CHT-SP condition
Other SNC415 tempers and conditions
SNC415 is listed in 8 conditions; see the grade overview at SNC415.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Spheroidize annealed | Softest condition, used when the part is cold headed, cold extruded or deep-formed before carburizing. | 360 | 570 | 30 | 155 HB | 7.2 % IACS |
ADefault Solution annealed | Standard stocked/soft condition for machining gear blanks before carburizing. | 420 | 640 | 25 | 170 HB | — |
Hot rolled | Cheapest mill condition for forging stock or parts that will be fully heat treated later. | 460 | 700 | 21 | 14 HRC | 7 % IACS |
Normalized | Grain-refined, more uniform condition for forgings prior to machining and carburizing. | 510 | 760 | 20 | 17 HRC | 7 % IACS |
Cold drawn | Bright, close-tolerance bar for automatic-lathe parts (pins, small shafts) that are later carburized. | 660 | 790 | 12 | 21 HRC | 7 % IACS |
Quenched and tempered | Use when the JIS G 4053 core mechanical requirements (≥780 MPa) must be certified, or for uncarburized through-hardened parts. | 660 | 850 | 19 | 26 HRC | — |
Carburized, quenched and low-temperature tempered | Final service condition for gears and splines: hard 58–62 HRC case over a tough ~30–40 HRC core. | 780 | 1,050 | 12 | 60 HRC | — |
CHT-SPThis page Carburized, hardened and shot peened | Pick for highly loaded transmission gears where root bending fatigue governs; peening adds compressive residual stress. | 900 | 1,150 | 10 | 60 HRC | 6.5 % IACS |
What is SNC415 CHT-SP?
SNC415 CHT-SP is SNC415 supplied in the CHT-SP condition — pick for highly loaded transmission gears where root bending fatigue governs; peening adds compressive residual stress. SNC415 CHT-SP has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 90% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi). SNC415 CHT-SP 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). A is the default condition FabDigit quotes; CHT-SP is available on request or by drawing note.
Advantages
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Difficult to weld — 8/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
SNC415 CHT-SP properties
Typical room-temperature values for SNC415 CHT-SP; 22 are specific to this condition. Other listed values are SNC415 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SNC415 CHT-SP 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
SNC415 CHT-SP has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 90% of steel grades. Elongation at break is 10% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SNC415 CHT-SP is rated for continuous service to 180°C (356 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12.2 µm/m·K (6.78 µin/in·°F).
Electrical3
SNC415 CHT-SP conducts electricity at 6.5 % IACS, worse than 77% of steel grades.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SNC415 CHT-SP takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
SNC415 CHT-SP's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (8/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SNC415 CHT-SP
Is SNC415 easy to machine?
Machine soft (annealed ~170 HB) with carbide at moderate speed and generous feed; the gummy Ni-bearing matrix smears at low feeds, and after carburizing only grinding/hard-turning with CBN is practical.
Can SNC415 be welded?
Low carbon makes it weldable with low-hydrogen electrodes, but Ni-Cr hardenability calls for 150–250 °C preheat and post-weld stress relief; never weld a carburized surface.
Can SNC415 be formed, bent or molded?
Good hot forging at 1100–1200 °C followed by normalizing; cold heading and upsetting are feasible in the spheroidize-annealed condition.
What surface finishes work on SNC415?
Carburize 900–930 °C, oil quench, temper 150–200 °C, then grind; protect with phosphate + oil, black oxide, zinc or Ni plating (bake after plating to avoid hydrogen embrittlement).
SNC415 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 | 0.12 – 0.18 | 0.15 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.35 – 0.65 | 0.5 |
| P | ≤ 0.03 | — |
| S | ≤ 0.03 | — |
| Ni | 2 – 2.5 | 2.25 |
| Cr | 0.2 – 0.5 | 0.35 |
| Curesidual, max | ≤ 0.3 | — |
| Fe | balance | — |
SNC415 CHT-SP — frequently asked
What is SNC415 CHT-SP used for?
SNC415 CHT-SP is typically used for transmission and reduction gears, pinion and drive shafts, splined shafts, gear pump shafts, cam followers and rollers and machine tool spindles. In short: tougher core than Cr grades; nickel-chromium carburizing steel; good cold-heading stock.
What is the yield strength of SNC415 CHT-SP?
SNC415 CHT-SP has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is SNC415 CHT-SP easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine soft (annealed ~170 HB) with carbide at moderate speed and generous feed; the gummy Ni-bearing matrix smears at low feeds, and after carburizing only grinding/hard-turning with CBN is practical.
Can SNC415 CHT-SP be welded?
Not readily — weldability is rated not recommended (8/100). Low carbon makes it weldable with low-hydrogen electrodes, but Ni-Cr hardenability calls for 150–250 °C preheat and post-weld stress relief; never weld a carburized surface.
What surface finishes work on SNC415 CHT-SP?
Carburize 900–930 °C, oil quench, temper 150–200 °C, then grind; protect with phosphate + oil, black oxide, zinc or Ni plating (bake after plating to avoid hydrogen embrittlement).
Can SNC415 CHT-SP be formed, bent or molded?
Good hot forging at 1100–1200 °C followed by normalizing; cold heading and upsetting are feasible in the spheroidize-annealed condition.
What is the maximum service temperature of SNC415 CHT-SP?
SNC415 CHT-SP is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SNC415-A and SNC415 CHT-SP?
A is the default condition — standard stocked/soft condition for machining gear blanks before carburizing. CHT-SP: pick for highly loaded transmission gears where root bending fatigue governs; peening adds compressive residual stress. Yield strength is 420 MPa in A versus 900 MPa in CHT-SP.
Sources
- JIS G 4053 — Low-alloyed steels for machine structural use — Japanese Industrial Standards Committee (2016)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (carburizing of Ni-Cr steels) — ASM International (1991)
- ASM Handbook Vol.16 — Machining (machinability ratings of alloy steels) — ASM International (1989)
- SAE J404 — Chemical Compositions of SAE Alloy Steels (3115/3310 reference) — SAE International (2009)
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.