Steel SNCM625
JIS SNCM625
SNCM625 is a JIS Ni-Cr-Mo alloy steel with carbon above the usual carburizing range, normally used quenched and tempered and occasionally carburized or nitrided for large, heavily loaded gear components.
Reference datasheet — SNCM625 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 QT condition
SNCM625 tempers and conditions
SNCM625 is supplied in 10 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 10 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Softest condition for deep machining, hobbing or cold work before final quench and temper. | 480 | 730 | 22 | 215 HB | — |
Hot rolled | Mill-supplied stock intended for re-heat-treatment; not for direct load-bearing use. | 570 | 880 | 16 | 25 HRC | 7.5 % IACS |
Normalized | Uniform fine-grain structure for large forgings before carburizing or final Q&T; note this grade air-hardens strongly. | 640 | 930 | 18 | 27 HRC | 7.4 % IACS |
Cold drawn | Small-diameter precision bar with better surface and straightness; strength from cold work, low ductility. | 700 | 850 | 11 | 24 HRC | 7.5 % IACS |
Q&T 28–32 HRC (high-temper, maximum toughness) | Pick when impact toughness and machinability after heat treatment matter more than peak strength. | 860 | 990 | 20 | 30 HRC | 7.2 % IACS |
QTDefault Quenched and tempered | Standard supplied condition: ≥940 MPa tensile with high toughness for shafts, large gear blanks and heavy-duty machine parts. | 880 | 1,000 | 20 | 30 HRC | — |
Q&T + gas/plasma nitrided | Choose for low-distortion wear and fatigue improvement on finish-machined Q&T parts. | 880 | 1,000 | 18 | 58 HRC | 7.2 % IACS |
Carburized, hardened and low-temper | For large gears and pins needing a hard wear case over a very tough, deeply hardened Ni-Cr-Mo core. | 950 | 1,150 | 12 | 60 HRC | 6.6 % IACS |
Q&T 32–36 HRC (medium temper) | Higher-strength gear and shaft condition, still readily machinable and a good nitriding base. | 990 | 1,120 | 17 | 34 HRC | 7.2 % IACS |
Q&T 36–40 HRC (low temper, high strength) | Near the practical hardness ceiling for this 0.25 % C grade; use where wear and strength dominate and toughness margin is accepted. | 1,100 | 1,250 | 14 | 38 HRC | 7.1 % IACS |
What is SNCM625?
SNCM625 is a JIS Ni-Cr-Mo alloy steel with carbon above the usual carburizing range, normally used quenched and tempered and occasionally carburized or nitrided for large, heavily loaded gear components. In the default condition it provides 880 MPa yield, 1000 MPa tensile, 20% elongation and about 290 HB (30 HRC) with service to 400 °C, and is available annealed, hot rolled, normalized, cold drawn or in QT hardness bands of 28–32, 32–36 and 36–40 HRC. High hardenability makes welding difficult and the steel has no corrosion resistance, so a protective finish is required. Where a deep carburized case over a very tough core is the priority, SNCM815 (9310) is the closer choice. SNCM625 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). SNCM625 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 89% of steel grades. Elongation at break is 20% and the elastic modulus is 206 GPa (29.9 Msi).
What is SNCM625 used for?
- Large industrial gears
- Heavy-duty drive shafts
- Gear pinions and gear blanks
- Spline shafts
- Mill and crane drive components
- Nitrided wear sleeves
Advantages
- High strength — 880 MPa (128 ksi), better than 89% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 25/100, worse than 77% of steel grades
- Limited formability — 22/100, worse than 76% of steel grades
SNCM625 properties
Typical room-temperature values for SNCM625-QT; bars are the position among steel grades.
Physical3
SNCM625 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
SNCM625 has a yield strength of 880 MPa (128 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 89% of steel grades. Elongation at break is 20% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
SNCM625 is rated for continuous service to 400°C (752 °F). It conducts heat at 36 W/m·K (20.8 BTU/hr·ft·°F), worse than 73% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SNCM625 conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of SNCM625 takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
SNCM625's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (25/100); formability poor (22/100).
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. SNCM625 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SNCM625
Is SNCM625 easy to machine?
Machine in the annealed or 28–32 HRC condition with rigid setups, coated carbide, ~80–140 m/min and generous feed; leave grinding stock for post-hardening finishing.
Can SNCM625 be welded?
Poor weldability due to high hardenability — preheat 250–350 °C, use low-hydrogen/matching filler, keep interpass temperature and temper immediately after welding.
Can SNCM625 be formed, bent or molded?
Hot forge 1050–1200 °C with slow controlled cooling (air hardens readily); cold forming limited to mild straightening in the annealed state.
SNCM625 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 | 0.2 – 0.3 | 0.25 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.35 – 0.6 | 0.48 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Ni | 3 – 3.5 | 3.25 |
| Cr | 1 – 1.5 | 1.25 |
| Mo | 0.15 – 0.3 | 0.22 |
| Curesidual, max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SNCM625?
Not anodizable — protect with oil, phosphate, black oxide, zinc or hard-chrome plating; nitriding or induction hardening gives wear resistance, and tempered martensite takes a fine 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
How much does SNCM625 cost?
SNCM625 is a standard-cost steel ($$), cheaper than about 71% 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.
SNCM625 — frequently asked
What is SNCM625 used for?
SNCM625 is typically used for large industrial gears, heavy-duty drive shafts, gear pinions and gear blanks, spline shafts, mill and crane drive components and nitrided wear sleeves. In short: high-hardenability Ni-Cr-Mo steel; heavy-section gear steel; supplied in HRC bands.
What is the yield strength of SNCM625?
SNCM625 has a typical yield strength of 880 MPa (128 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is SNCM625 easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in the annealed or 28–32 HRC condition with rigid setups, coated carbide, ~80–140 m/min and generous feed; leave grinding stock for post-hardening finishing.
Can SNCM625 be welded?
Not readily — weldability is rated poor (25/100). Poor weldability due to high hardenability — preheat 250–350 °C, use low-hydrogen/matching filler, keep interpass temperature and temper immediately after welding.
What surface finishes work on SNCM625?
Not anodizable — protect with oil, phosphate, black oxide, zinc or hard-chrome plating; nitriding or induction hardening gives wear resistance, and tempered martensite takes a fine polish.
Can SNCM625 be formed, bent or molded?
Hot forge 1050–1200 °C with slow controlled cooling (air hardens readily); cold forming limited to mild straightening in the annealed state.
What is the maximum service temperature of SNCM625?
SNCM625 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 SNCM625-QT and SNCM625-A?
QT is the default condition — standard supplied condition: ≥940 MPa tensile with high toughness for shafts, large gear blanks and heavy-duty machine parts. A: softest condition for deep machining, hobbing or cold work before final quench and temper. Yield strength is 880 MPa in QT versus 480 MPa in A.
How much does SNCM625 cost?
SNCM625 is a standard-cost steel ($$), cheaper than about 71% 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 G4103 — Nickel-chromium-molybdenum steels — Japanese Standards Association (2019)
- 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)
- Machinery's Handbook, 31st ed. (machinability and 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.