Steel SNCM630
JIS SNCM630
SNCM630 is a nickel–chromium–molybdenum through-hardening steel roughly comparable to AISI 4340, available annealed, normalised, hot-rolled, cold-drawn, quenched-and-tempered from 30–34 HRC up to 46–50 HRC, and Q&T plus nitrided.
Reference datasheet — SNCM630 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-H condition
SNCM630 tempers and conditions
SNCM630 is supplied in 11 conditions, soft to hard. QT-H is the default FabDigit quotes; the values on this page are for it.
Compare all 11 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick for deep machining, cold sawing or before final quench-and-temper. | 640 | 850 | 20 | 24 HRC | — |
Hot rolled | Cheapest stock form for parts that will be fully heat treated after rough machining. | 700 | 980 | 16 | 29 HRC | 5.8 % IACS |
Normalized | Pick for uniform grain and moderate strength on large forgings before final heat treatment. | 780 | 1,030 | 17 | 31 HRC | — |
Cold drawn | Pick for close-tolerance small-diameter bar where a bright finish is needed before final heat treatment. | 800 | 950 | 12 | 28 HRC | 5.7 % IACS |
high-temperature temper | Pick when maximum toughness and machinability are wanted in a heat-treated part. | 910 | 1,030 | 18 | 32 HRC | — |
QT-HDefault Q&T per JIS G4103 | Standard commercial supply condition: ≥1080 MPa tensile with good toughness for shafts and high-load fasteners. | 1,000 | 1,150 | 17 | 34 HRC | — |
Q&T then gas/plasma nitrided | Pick when a Q&T core must carry load while the surface needs wear and fatigue resistance without distortion. | 1,000 | 1,150 | 14 | 34 HRC | 5.5 % IACS |
Q&T 34–38 HRC | Balanced strength/toughness condition for gear shafts and heavily loaded machine parts. | 1,050 | 1,170 | 16 | 36 HRC | — |
Q&T 38–42 HRC | Pick for high-strength airframe/landing-gear-type parts where some toughness is still required. | 1,180 | 1,300 | 13 | 40 HRC | — |
low-temperature temper | Pick for maximum strength shafts, tool holders and dies; grind after treatment. | 1,330 | 1,450 | 11 | 44 HRC | — |
near as-quenched strength | Only for wear-critical, low-toughness-demand parts; notch and hydrogen sensitivity are high. | 1,450 | 1,600 | 9 | 48 HRC | — |
What is SNCM630?
SNCM630 is a nickel–chromium–molybdenum through-hardening steel roughly comparable to AISI 4340, available annealed, normalised, hot-rolled, cold-drawn, quenched-and-tempered from 30–34 HRC up to 46–50 HRC, and Q&T plus nitrided. Default Q&T values are 1000 MPa yield, 1150 MPa tensile, 17 % elongation and 325 HB (34 HRC) with service to 400 °C, giving deep hardenability and toughness in large sections for landing-gear parts, high-strength bolts and heavily loaded shafts. Machinability is low (38/100) and weldability poor, and alloy cost is higher than 4140, which is the usual step down when section size allows. SNCM630 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). SNCM630 has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 92% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
What is SNCM630 used for?
- aircraft landing gear
- high-strength bolts
- shafts
Advantages
- High strength — 1,000 MPa (145 ksi), better than 92% of steel grades
- Polishes to a fine finish — 72/100, better than 92% of steel grades
Limitations
- High embodied carbon — 2.5 kg CO₂/kg, worse than 82% of steel grades
- Low electrical conductivity — 5.5 % IACS, worse than 81% of steel grades
- Difficult to machine — 38/100, worse than 80% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
- Limited formability — 22/100, worse than 76% of steel grades
SNCM630 properties
Typical room-temperature values for SNCM630-QT-H; bars are the position among steel grades.
Physical3
SNCM630 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).
Mechanical16
SNCM630 has a yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 92% of steel grades. Elongation at break is 17% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SNCM630 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 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SNCM630 conducts electricity at 5.5 % IACS, worse than 81% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (14/100), better than 70% of steel grades.
Sustainability4
Producing a kilogram of SNCM630 takes about 34 MJ of energy and emits 2.5 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
SNCM630's machinability is fair (38/100, worse than 80% of steel grades); weldability poor (30/100); 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. SNCM630 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SNCM630
Is SNCM630 easy to machine?
Machine in the annealed or ≤34 HRC condition with rigid setups, carbide tooling and 60–120 m/min; above 40 HRC use ceramic/CBN or grinding.
Can SNCM630 be welded?
Poor weldability due to high hardenability — preheat 250–350 °C, low-hydrogen or matching filler, and immediately post-weld temper below the original tempering temperature.
Can SNCM630 be formed, bent or molded?
Hot forge 1150–900 °C then slow cool/anneal; cold forming is impractical above ~250 HB.
SNCM630 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 | 0.25 – 0.35 | 0.3 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.35 – 0.6 | 0.48 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Ni | 2.5 – 3.5 | 3 |
| Cr | 2.5 – 3.5 | 3 |
| Mo | 0.5 – 0.7 | 0.6 |
| Curesidual max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SNCM630?
Not anodizable; use phosphate + oil, black oxide, zinc or Zn-Ni plating (bake 190 °C ≥4 h to de-embrittle), nitriding or hard chrome for wear.
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 SNCM630 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 4340
How much does SNCM630 cost?
SNCM630 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.
SNCM630 — frequently asked
What is SNCM630 used for?
SNCM630 is typically used for aircraft landing gear, high-strength bolts and shafts. In short: highest strength in family; 4340-class Ni-Cr-Mo steel; deep-hardening heavy sections.
What is the yield strength of SNCM630?
SNCM630 has a typical yield strength of 1,000 MPa (145 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 92% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is SNCM630 easy to machine?
Not especially — machinability is rated fair (38/100, worse than 80% of steel grades). Machine in the annealed or ≤34 HRC condition with rigid setups, carbide tooling and 60–120 m/min; above 40 HRC use ceramic/CBN or grinding.
Can SNCM630 be welded?
Not readily — weldability is rated poor (30/100). Poor weldability due to high hardenability — preheat 250–350 °C, low-hydrogen or matching filler, and immediately post-weld temper below the original tempering temperature.
What surface finishes work on SNCM630?
Not anodizable; use phosphate + oil, black oxide, zinc or Zn-Ni plating (bake 190 °C ≥4 h to de-embrittle), nitriding or hard chrome for wear.
Can SNCM630 be formed, bent or molded?
Hot forge 1150–900 °C then slow cool/anneal; cold forming is impractical above ~250 HB.
What is the maximum service temperature of SNCM630?
SNCM630 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 SNCM630 QT-H and SNCM630-A?
QT-H is the default condition — standard commercial supply condition: ≥1080 MPa tensile with good toughness for shafts and high-load fasteners. A: pick for deep machining, cold sawing or before final quench-and-temper. Yield strength is 1,000 MPa in QT-H versus 640 MPa in A.
How much does SNCM630 cost?
SNCM630 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 — JSA (2018)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- ASM Handbook Vol.16: Machining — ASM International (1989)
- MMPDS-style typical property data for 4340-class low-alloy steels — Battelle/FAA (2022)
- GB/T 3077 (30Cr2Ni2Mo comparison) — SAC (2015)
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.