Steel SNCM625 QT-36-40HRC
Hardness band
JIS SNCM625
Near the practical hardness ceiling for this 0.25 % C grade; use where wear and strength dominate and toughness margin is accepted.
Values for the QT-36-40HRC condition
Other SNCM625 tempers and conditions
SNCM625 is listed in 10 conditions; see the grade overview at SNCM625.
- A
- HR
- N
- CD
- QT-28-32HRC
- QT
- NIT
- CARB
- QT-32-36HRC
- QT-36-40HRC
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 |
QT-36-40HRCThis page 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 QT-36-40HRC?
SNCM625 QT-36-40HRC is SNCM625 heat treated to QT-36-40HRC — near the practical hardness ceiling for this 0.25 % C grade; use where wear and strength dominate and toughness margin is accepted. SNCM625 QT-36-40HRC has a yield strength of 1,100 MPa (160 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Elongation at break is 14% and the elastic modulus is 206 GPa (29.9 Msi). SNCM625 QT-36-40HRC 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). QT is the default condition FabDigit quotes; QT-36-40HRC is available on request or by drawing note.
Advantages
- High strength — 1,100 MPa (160 ksi), better than 93% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Limited formability — 13/100, worse than 90% of steel grades
- Difficult to machine — 30/100, worse than 89% of steel grades
- Difficult to weld — 18/100, worse than 87% of steel grades
- Limited ductility — 14%, worse than 75% of steel grades
- Poor heat conductor — 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades
SNCM625 QT-36-40HRC properties
Typical room-temperature values for SNCM625 QT-36-40HRC; 22 are specific to this condition. Other listed values are SNCM625 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
SNCM625 QT-36-40HRC 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 QT-36-40HRC has a yield strength of 1,100 MPa (160 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Elongation at break is 14% and the elastic modulus is 206 GPa (29.9 Msi).
Thermal6
SNCM625 QT-36-40HRC is rated for continuous service to 350°C (662 °F). It conducts heat at 35 W/m·K (20.2 BTU/hr·ft·°F), worse than 75% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
SNCM625 QT-36-40HRC conducts electricity at 7.1 % IACS, worse than 72% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of SNCM625 QT-36-40HRC 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 QT-36-40HRC's machinability is poor (30/100, worse than 89% of steel grades); weldability poor (18/100); formability not recommended (13/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with SNCM625 QT-36-40HRC
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.
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.
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 | — |
SNCM625 QT-36-40HRC — frequently asked
What is SNCM625 QT-36-40HRC used for?
SNCM625 QT-36-40HRC 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 QT-36-40HRC?
SNCM625 QT-36-40HRC has a typical yield strength of 1,100 MPa (160 ksi) and a tensile strength of 1,250 MPa (181 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 10 listed tempers.
Is SNCM625 QT-36-40HRC easy to machine?
Not especially — machinability is rated poor (30/100, worse than 89% 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 QT-36-40HRC be welded?
Not readily — weldability is rated poor (18/100). 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 QT-36-40HRC?
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 QT-36-40HRC 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 QT-36-40HRC?
SNCM625 QT-36-40HRC is rated for continuous use to about 350°C (662 °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.
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. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.