Steel SNCM447 QT-40-44HRC
Hardness band
JIS SNCM447
Use the 480–520 °C temper to 40–44 HRC for high-strength fasteners and heavily loaded spline shafts; avoid the 450–550 °C temper embrittlement range and cool rapidly after tempering.
Values for the QT-40-44HRC condition
Other SNCM447 tempers and conditions
SNCM447 is listed in 11 conditions; see the grade overview at SNCM447.
Compare all 11 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 when large machining allowances or cold forming come first; hardness is lowest at 210 HB with the best cutting behaviour. | 480 | 750 | 22 | 210 HB | — |
Hot rolled | Choose the untreated hot-rolled bar as the cheapest raw form when you will anneal or quench and temper in house, accepting coarse tolerances and surface finish. | 570 | 900 | 15 | 27 HRC | 7 % IACS |
Normalized | Use normalizing at 850–880 °C with air cooling to homogenize and refine forged blanks as preparatory heat treatment before quenching and tempering; 620 MPa yield at 285 HB. | 620 | 950 | 14 | 29 HRC | 7 % IACS |
Cold drawn | Pick annealed then cold-drawn bright bar for precise small-diameter shaft stock that machines directly and can still be quenched and tempered later; elongation falls to 12%. | 730 | 880 | 12 | 25 HRC | 7 % IACS |
620–660 °C | Choose the high temper near 620–660 °C to 28–32 HRC for toughness-driven large-section forgings such as crankshafts and coarse-module gear blanks that still need machining. | 860 | 1,000 | 18 | 30 HRC | — |
QT-JISDefault Q&T | Use the standard JIS G4053 delivery state, oil quenched at 820–870 °C and tempered at 580–680 °C to 302–363 HB, for heavily loaded shafts, gears and connecting rods. | 980 | 1,100 | 16 | 34 HRC | — |
Q&T + Nitrided | Use for precision shafts and lead screws needing a 550–650 HV wear surface with low distortion; gas or ion nitriding runs below the tempering temperature so core properties are retained. | 980 | 1,100 | 15 | 55 HRC | 7 % IACS |
Q&T + Induction Hardened | Pick when a tough quenched-and-tempered core must carry a 55–60 HRC induction-hardened case on journals or tooth flanks; the compressive surface stress raises contact fatigue life. | 1,000 | 1,150 | 14 | 57 HRC | 7 % IACS |
540–600 °C | Pick the 540–600 °C temper to 34–38 HRC as the usual strength-versus-toughness compromise for shafts and drive components, giving 1080 MPa yield at 14% elongation. | 1,080 | 1,200 | 14 | 36 HRC | — |
QT-40-44HRCThis page 480–520 °C | Use the 480–520 °C temper to 40–44 HRC for high-strength fasteners and heavily loaded spline shafts; avoid the 450–550 °C temper embrittlement range and cool rapidly after tempering. | 1,280 | 1,400 | 11 | 42 HRC | — |
200–300 °C | Choose the low-temperature temper (about 200–300 °C) for tools, ejector pins and highly stressed pins needing 48–52 HRC and maximum wear resistance; toughness drops markedly, elongation only 8 %. | 1,500 | 1,750 | 8 | 50 HRC | — |
What is SNCM447 QT-40-44HRC?
SNCM447 QT-40-44HRC is SNCM447 heat treated to QT-40-44HRC — use the 480–520 °C temper to 40–44 HRC for high-strength fasteners and heavily loaded spline shafts; avoid the 450–550 °C temper embrittlement range and cool rapidly after tempering. SNCM447 QT-40-44HRC has a yield strength of 1,280 MPa (186 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 95% of steel grades. Elongation at break is 11% and the elastic modulus is 205 GPa (29.7 Msi). SNCM447 QT-40-44HRC 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). QT-JIS is the default condition FabDigit quotes; QT-40-44HRC is available on request or by drawing note.
Advantages
- High strength — 1,280 MPa (186 ksi), better than 95% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 11%, worse than 89% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
SNCM447 QT-40-44HRC properties
Typical room-temperature values for SNCM447 QT-40-44HRC; 11 are specific to this condition. Other listed values are SNCM447 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SNCM447 QT-40-44HRC 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
SNCM447 QT-40-44HRC has a yield strength of 1,280 MPa (186 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 95% of steel grades. Elongation at break is 11% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
SNCM447 QT-40-44HRC is rated for continuous service to 330°C (626 °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
SNCM447 QT-40-44HRC conducts electricity at 7 % IACS, worse than 74% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of SNCM447 QT-40-44HRC takes about 30 MJ of energy and emits 2.3 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 25%.
Manufacturability7
SNCM447 QT-40-44HRC's machinability is fair (42/100, worse than 73% of steel grades); weldability poor (25/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SNCM447 QT-40-44HRC
Is SNCM447 easy to machine?
Machining is most economical in the annealed condition or after quench and temper to 32 HRC or below. At 40 HRC and above use coated carbide or CBN with low speed, high feed and full coolant; complete deep holes and threads before hardening where possible.
Can SNCM447 be welded?
High carbon equivalent and strong hardening tendency mean welding is generally not recommended. When unavoidable, use low-hydrogen consumables, 200-300 °C preheat, controlled interpass temperature and an immediate post-weld temper slightly below the original tempering temperature.
Can SNCM447 be formed, bent or molded?
Warm forming and forging are practical only from the annealed condition — start at 1150-1200 °C and finish at 850 °C or above. Slow cool after forging and normalize or anneal to remove flake (white spots) and residual stress.
What surface finishes work on SNCM447?
No corrosion resistance; typical finishes are black oxide, phosphate, Dacromet, zinc plating or hard chrome. Bake plated high-strength parts at 190-220 °C for hydrogen removal, and shot peen to raise fatigue life significantly.
SNCM447 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 | 0.44 – 0.5 | 0.47 |
| 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 element limit | ≤ 0.3 | — |
| Fe | balance | — |
SNCM447 QT-40-44HRC — frequently asked
What is SNCM447 QT-40-44HRC used for?
SNCM447 QT-40-44HRC is typically used for heavy-duty shafts, large gears and high-strength forgings. In short: highest strength JIS Ni-Cr-Mo; deep hardenability in heavy sections; hardens to 48-52 HRC.
What is the yield strength of SNCM447 QT-40-44HRC?
SNCM447 QT-40-44HRC has a typical yield strength of 1,280 MPa (186 ksi) and a tensile strength of 1,400 MPa (203 ksi) — stronger than 95% of steel grades. Strength varies by condition: see the 11 listed tempers.
Is SNCM447 QT-40-44HRC easy to machine?
Not especially — machinability is rated fair (42/100, worse than 73% of steel grades). Machining is most economical in the annealed condition or after quench and temper to 32 HRC or below. At 40 HRC and above use coated carbide or CBN with low speed, high feed and full coolant; complete deep holes and threads before hardening where possible.
Can SNCM447 QT-40-44HRC be welded?
Not readily — weldability is rated poor (25/100). High carbon equivalent and strong hardening tendency mean welding is generally not recommended. When unavoidable, use low-hydrogen consumables, 200-300 °C preheat, controlled interpass temperature and an immediate post-weld temper slightly below the original tempering temperature.
What surface finishes work on SNCM447 QT-40-44HRC?
No corrosion resistance; typical finishes are black oxide, phosphate, Dacromet, zinc plating or hard chrome. Bake plated high-strength parts at 190-220 °C for hydrogen removal, and shot peen to raise fatigue life significantly.
Can SNCM447 QT-40-44HRC be formed, bent or molded?
Warm forming and forging are practical only from the annealed condition — start at 1150-1200 °C and finish at 850 °C or above. Slow cool after forging and normalize or anneal to remove flake (white spots) and residual stress.
What is the maximum service temperature of SNCM447 QT-40-44HRC?
SNCM447 QT-40-44HRC is rated for continuous use to about 330°C (626 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between SNCM447 QT-JIS and SNCM447-A?
QT-JIS is the default condition — use the standard JIS G4053 delivery state, oil quenched at 820–870 °C and tempered at 580–680 °C to 302–363 HB, for heavily loaded shafts, gears and connecting rods. A: pick the full anneal at 820–860 °C with furnace cooling when large machining allowances or cold forming come first; hardness is lowest at 210 HB with the best cutting behaviour. Yield strength is 980 MPa in QT-JIS versus 480 MPa in A.
Sources
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture (4340 data) — ASM International (1996)
- SAE J404 / AISI 4340 — SAE International (2009)
- Machinery's Handbook (machinability ratings) — Industrial Press (2020)
- 40CrNiMoA/SNCM447 — Mysteel / 1688 (2025)
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.