Steel SNCM431
JIS SNCM431
SNCM431 is a JIS G 4103 through-hardening nickel-chromium-molybdenum steel cross-referenced to AISI 8630, combining moderate strength with good toughness in medium sections.
Reference datasheet — SNCM431 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
SNCM431 tempers and conditions
SNCM431 is supplied in 9 conditions, soft to hard. QT is the default FabDigit quotes; the values on this page are for it.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Pick the full anneal at 820–860 °C with furnace cooling for post-forging softening, heavy machining or as stock before re-hardening, giving the lowest 200 HB and best machinability. | 470 | 690 | 23 | 200 HB | — |
Hot rolled | Choose as-rolled bar as the lowest-cost delivery form for blanks that will be quenched and tempered or forged later; properties scatter around 520 MPa yield and 235 HB. | 520 | 800 | 19 | 21 HRC | 8 % IACS |
Normalized | Use normalizing at 870–900 °C with air cooling to refine and homogenize forged structure as an intermediate or delivery state, stronger than annealed at 570 MPa yield yet still machinable. | 570 | 850 | 20 | 24 HRC | — |
Cold drawn | Pick annealed and cold-drawn bar for accurate small diameters and bright surface ready for direct machining, accepting 12% elongation and residual stress from drawing. | 650 | 780 | 12 | 20 HRC | 8 % IACS |
Stress relieved | Apply stress relief at 550–650 °C after welding or rough machining to stabilize dimensions while keeping essentially quench-and-temper hardness at 265 HB. | 730 | 880 | 20 | 26 HRC | 7.8 % IACS |
QTDefault Quenched and tempered | Use the common delivery state, oil quenched at 820–870 °C and tempered at 570–670 °C to the 830 MPa class, for shafts, gear blanks and rods needing strength with 20% elongation. | 760 | 900 | 20 | 28 HRC | — |
tempered ~590–620 °C | Choose the 28–32 HRC temper at 590–620 °C as the general medium-strength setting for mid-section drive shafts, balancing 850 MPa yield, 18% elongation and machinability. | 850 | 990 | 18 | 30 HRC | — |
tempered ~540–580 °C | Pick tempering at 540–580 °C to 32–36 HRC for shafts and fasteners under higher contact or bending stress; yield reaches 980 MPa with slightly reduced impact toughness. | 980 | 1,110 | 16 | 34 HRC | — |
tempered ~480–520 °C | Use the 480–520 °C temper to 36–40 HRC for small high-strength parts such as pins and high-tensile bolts; toughness and machinability drop and hydrogen embrittlement must be controlled. | 1,120 | 1,250 | 13 | 38 HRC | — |
What is SNCM431?
SNCM431 is a JIS G 4103 through-hardening nickel-chromium-molybdenum steel cross-referenced to AISI 8630, combining moderate strength with good toughness in medium sections. It is chosen for shafts, structural bolts and forgings and is supplied as hot-rolled and cold-drawn bar in annealed, normalized, stress-relieved and quenched-and-tempered conditions from 28-32 HRC to 36-40 HRC (760 MPa yield, 900 MPa tensile, 20% elongation, 275 HB / 28 HRC). Weldability is limited (score 40, CE 0.7-0.8) and corrosion resistance is nil, so preheat and a protective coating are required; service is limited to about 400 °C. SNCM439 is the next step up in strength. SNCM431 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). SNCM431 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 85% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
What is SNCM431 used for?
- shafts
- structural bolts
- pressure vessel components
Advantages
- High strength — 760 MPa (110 ksi), better than 85% of steel grades
SNCM431 properties
Typical room-temperature values for SNCM431-QT; bars are the position among steel grades.
Physical3
SNCM431 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
SNCM431 has a yield strength of 760 MPa (110 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 85% of steel grades. Elongation at break is 20% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SNCM431 is rated for continuous service to 400°C (752 °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
SNCM431 conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SNCM431 takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
SNCM431's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (40/100); 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. SNCM431 is highlighted; hover a dot for its name, or open the interactive family chart.
Working with SNCM431
Is SNCM431 easy to machine?
Annealed and normalized material machines most easily (about 55-65% of AISI 1212). Above 30 HRC after quench and temper, use coated carbide with lower speed, higher feed and generous coolant.
Can SNCM431 be welded?
Carbon equivalent is about 0.7-0.8, so use 200-300 °C preheat and low-hydrogen consumables, followed by a 580-650 °C temper to avoid martensitic cracking.
Can SNCM431 be formed, bent or molded?
Forge at approximately 1100-1200 °C with finishing temperature no lower than 850 °C. Cold forming is restricted to light bending and upsetting in the annealed condition.
SNCM431 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 G4053 | 0.27 – 0.35 | 0.31 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.03 | |
| S | ≤ 0.03 | |
| Ni | 1.6 – 2 | 1.8 |
| Cr | 0.6 – 1 | 0.8 |
| Mo | 0.15 – 0.3 | 0.22 |
| Curesidual max | ≤ 0.3 | |
| Fe | balance |
What surface finishes work on SNCM431?
No inherent corrosion resistance — apply black oxide, phosphate, zinc or chrome plating, or paint. Electroplated parts in the high-strength tempers require hydrogen bake-out at 190-210 °C for 4-24 h.
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 SNCM431 in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Similar grades
- 8630
How much does SNCM431 cost?
SNCM431 is a budget-cost steel ($), cheaper than about 90% 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.
SNCM431 — frequently asked
What is SNCM431 used for?
SNCM431 is typically used for shafts, structural bolts and pressure vessel components. In short: balanced strength and toughness; through-hardening Ni-Cr-Mo bar; weldable with preheat.
What is the yield strength of SNCM431?
SNCM431 has a typical yield strength of 760 MPa (110 ksi) and a tensile strength of 900 MPa (131 ksi) — stronger than 85% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is SNCM431 easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Annealed and normalized material machines most easily (about 55-65% of AISI 1212). Above 30 HRC after quench and temper, use coated carbide with lower speed, higher feed and generous coolant.
Can SNCM431 be welded?
With care — weldability is rated fair (40/100). Carbon equivalent is about 0.7-0.8, so use 200-300 °C preheat and low-hydrogen consumables, followed by a 580-650 °C temper to avoid martensitic cracking.
What surface finishes work on SNCM431?
No inherent corrosion resistance — apply black oxide, phosphate, zinc or chrome plating, or paint. Electroplated parts in the high-strength tempers require hydrogen bake-out at 190-210 °C for 4-24 h.
Can SNCM431 be formed, bent or molded?
Forge at approximately 1100-1200 °C with finishing temperature no lower than 850 °C. Cold forming is restricted to light bending and upsetting in the annealed condition.
What is the maximum service temperature of SNCM431?
SNCM431 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 SNCM431-QT and SNCM431-A?
QT is the default condition — use the common delivery state, oil quenched at 820–870 °C and tempered at 570–670 °C to the 830 MPa class, for shafts, gear blanks and rods needing strength with 20% elongation. A: pick the full anneal at 820–860 °C with furnace cooling for post-forging softening, heavy machining or as stock before re-hardening, giving the lowest 200 HB and best machinability. Yield strength is 760 MPa in QT versus 470 MPa in A.
How much does SNCM431 cost?
SNCM431 is a budget-cost steel ($), cheaper than about 90% 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
- SAE J404 Chemical Compositions of SAE Alloy Steels (8630) — SAE International (2021)
- 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)
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.