Steel SNCM815
JIS SNCM815 · UNS G93106
SNCM815 (AISI 9310, UNS G93106) is a high-alloy Ni-Cr-Mo carburizing steel with roughly 4% nickel, used where a deep hardened case must sit on a very tough core.
Reference datasheet — SNCM815 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 NT condition
SNCM815 tempers and conditions
SNCM815 is supplied in 7 conditions, soft to hard. NT is the default FabDigit quotes; the values on this page are for it.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition — pick it for heavy rough machining, deep drilling or cold sizing before carburizing. | 560 | 800 | 22 | 200 HB | — |
Normalized | Grain-refining treatment after forging; usually followed by tempering or annealing before machining. | 720 | 1,000 | 16 | 31 HRC | 7 % IACS |
NTDefault normalized and tempered (machining condition, ≤302 HB) | The standard aircraft-quality bar/forging supply condition: uniform, machinable, ready for gear cutting and subsequent carburizing. | 750 | 950 | 18 | 26 HRC | — |
Hot rolled | Cheapest mill condition for re-forging or re-heat-treating; too hard and variable for direct machining. | 800 | 1,100 | 13 | 36 HRC | 7 % IACS |
Cold drawn | Small-diameter precision bar for pins and small gear blanks where tight tolerance and good surface matter. | 820 | 950 | 12 | 29 HRC | 7 % IACS |
Quenched and tempered | Use where the part is loaded through-section without carburizing (shafts, bolts, high-toughness structural links). | 980 | 1,180 | 15 | 36 HRC | — |
Carburized and hardened | The service condition for gears: deep 0.8–2.0 mm case for contact/bending fatigue with a very tough 4% Ni core. | 1,050 | 1,250 | 13 | 61 HRC | — |
What is SNCM815?
SNCM815 (AISI 9310, UNS G93106) is a high-alloy Ni-Cr-Mo carburizing steel with roughly 4% nickel, used where a deep hardened case must sit on a very tough core. In the normalized-and-tempered default condition it gives 750 MPa yield, 950 MPa tensile, 18% elongation and about 262 HB (26 HRC), with service to 400 °C; forms include bar, forged gear blanks and carburized (CH) or cold-drawn stock. Machinability is low at about 45% of AISI 1212, weldability is poor, and the steel offers no corrosion resistance. Where loads are lower, 15CrNi6 or 17CrNiMo6-4 are less costly alternatives. SNCM815 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). SNCM815 has a yield strength of 750 MPa (109 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 84% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
What is SNCM815 used for?
- Heavy-duty aerospace and helicopter gears
- Gearbox pinions
- Transmission shafts
- Bevel and spiral bevel gears
- Splined drive shafts
- High-load bearing races
Advantages
- High strength — 750 MPa (109 ksi), better than 84% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- High embodied carbon — 2.6 kg CO₂/kg, worse than 87% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
SNCM815 properties
Typical room-temperature values for SNCM815-NT; bars are the position among steel grades.
Physical3
SNCM815 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).
Mechanical14
SNCM815 has a yield strength of 750 MPa (109 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 84% of steel grades. Elongation at break is 18% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SNCM815 is rated for continuous service to 400°C (752 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.6 µm/m·K (6.44 µin/in·°F).
Electrical3
SNCM815 conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of SNCM815 takes about 36 MJ of energy and emits 2.6 kg of CO₂ — more than 89% of steel grades. Typical recycled content is 25%.
Manufacturability6
SNCM815's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (25/100); formability poor (30/100).
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. SNCM815 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SNCM815
Is SNCM815 easy to machine?
Machine in the annealed or N+T condition (~45% of 1212); gummy and work-hardening — use rigid setups, positive-rake carbide, generous coolant, and finish-grind after carburizing to remove heat-treat distortion.
Can SNCM815 be welded?
Poor weldability: high hardenability and 4% Ni give hard, crack-prone HAZ — if unavoidable, use low-hydrogen filler, 200–300 °C preheat and immediate post-weld temper; never weld carburized surfaces.
Can SNCM815 be formed, bent or molded?
Hot forge 1150–1200 °C, stop above 950 °C, then normalize and temper; cold forming limited to light straightening and thread rolling in the annealed condition.
SNCM815 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 SNCM815 | 0.12 – 0.18 | 0.15 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.3 – 0.6 | 0.45 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Ni | 4 – 4.5 | 4.25 |
| Cr | 0.7 – 1 | 0.85 |
| Mo | 0.15 – 0.3 | 0.22 |
| Curesidual, max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SNCM815?
Shot peen tooth roots for fatigue; protect with oil, black oxide, phosphate or thin dense chrome — no anodizing, and avoid unbaked electroplating on high-strength sections due to hydrogen embrittlement.
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 SNCM815 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- UNS
- G93106
- Similar grades
- 9310
How much does SNCM815 cost?
SNCM815 is a premium-cost steel ($$$), cheaper than about 51% 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.
SNCM815 — frequently asked
What is SNCM815 used for?
SNCM815 is typically used for heavy-duty aerospace and helicopter gears, gearbox pinions, transmission shafts, bevel and spiral bevel gears, splined drive shafts and high-load bearing races. In short: deep case, tough core; 4% Ni carburizing grade; aerospace gear standard.
What is the yield strength of SNCM815?
SNCM815 has a typical yield strength of 750 MPa (109 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 84% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is SNCM815 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or N+T condition (~45% of 1212); gummy and work-hardening — use rigid setups, positive-rake carbide, generous coolant, and finish-grind after carburizing to remove heat-treat distortion.
Can SNCM815 be welded?
Not readily — weldability is rated poor (25/100). Poor weldability: high hardenability and 4% Ni give hard, crack-prone HAZ — if unavoidable, use low-hydrogen filler, 200–300 °C preheat and immediate post-weld temper; never weld carburized surfaces.
What surface finishes work on SNCM815?
Shot peen tooth roots for fatigue; protect with oil, black oxide, phosphate or thin dense chrome — no anodizing, and avoid unbaked electroplating on high-strength sections due to hydrogen embrittlement.
Can SNCM815 be formed, bent or molded?
Hot forge 1150–1200 °C, stop above 950 °C, then normalize and temper; cold forming limited to light straightening and thread rolling in the annealed condition.
What is the maximum service temperature of SNCM815?
SNCM815 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 SNCM815-NT and SNCM815-CH?
NT is the default condition — the standard aircraft-quality bar/forging supply condition: uniform, machinable, ready for gear cutting and subsequent carburizing. CH: the service condition for gears: deep 0.8–2.0 mm case for contact/bending fatigue with a very tough 4% Ni core. Yield strength is 750 MPa in NT versus 1,050 MPa in CH.
How much does SNCM815 cost?
SNCM815 is a premium-cost steel ($$$), cheaper than about 51% 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 4103 — Nickel-chromium-molybdenum steels — JSA (2018)
- AMS 6265 — Steel bars/forgings 3.2Ni-1.2Cr-0.12Mo (9310), premium aircraft quality — SAE International (2019)
- SAE J404 — Chemical compositions of SAE alloy steels (9310) — SAE International (2020)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.4A — Steel Heat Treating Fundamentals (carburizing) — ASM International (2013)
- ASM Handbook Vol.16 — Machining — ASM International (1989)
- MMPDS-typical low-alloy steel elastic and physical constants — Battelle/FAA (2023)
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.