Steel 41CrAlMo7-10 +QT650
Heat-treated state
EN 41CrAlMo7-10 · GB 38CrMoAlA, 38KhMYuA
+QT650 = quenched and tempered, Rp0.2 ≥ 650 MPa
Same cycle on medium sections where mass effect lowers the through-hardened strength class.
Values for the +QT650 condition
Other 41CrAlMo7-10 tempers and conditions
41CrAlMo7-10 is listed in 7 conditions; see the grade overview at 41CrAlMo7-10.
Compare all 7 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick for heavy stock removal, deep-hole drilling or cold sawing before the customer's own quench-and-temper cycle. | 460 | 760 | 18 | 225 HB | — |
Normalized | Intermediate condition after forging to refine grain before quench-and-temper; rarely a final delivery state. | 600 | 900 | 15 | 28 HRC | 7.2 % IACS |
Quenched and tempered, Rp0.2 ≥ 600 MPa | Heavy forged sections and large rolls where hardenability limits core properties. | 650 | 900 | 16 | 28 HRC | 6.9 % IACS |
+QT650This page Quenched and tempered, Rp0.2 ≥ 650 MPa | Same cycle on medium sections where mass effect lowers the through-hardened strength class. | 700 | 950 | 15 | 31 HRC | 6.9 % IACS |
+QT750Default Quenched and tempered, Rp0.2 ≥ 750 MPa | Standard stocked bar condition: oil/water quench from ~930 °C + temper ~600–680 °C, ready for finish machining and subsequent nitriding. | 800 | 1,050 | 14 | 34 HRC | — |
+QT + gas/plasma nitrided | Final service condition: hard AlN-rich case ≥950 HV, 0.3–0.8 mm deep, on a 950–1150 MPa core — for wear-loaded shafts, gears and extruder screws. | 800 | 1,050 | 12 | 67 HRC | — |
Quenched, tempered and peeled/ground bright bar | Pick when close diameter tolerance (h9/h11) and a decarb-free surface are needed straight from stock. | 800 | 1,050 | 14 | 34 HRC | 6.9 % IACS |
What is 41CrAlMo7-10 +QT650?
41CrAlMo7-10 +QT650 is 41CrAlMo7-10 heat treated to +QT650 — same cycle on medium sections where mass effect lowers the through-hardened strength class. 41CrAlMo7-10 +QT650 has a yield strength of 700 MPa (102 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 81% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi). 41CrAlMo7-10 +QT650 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F). +QT750 is the default condition FabDigit quotes; +QT650 is available on request or by drawing note.
Advantages
- High service temperature — 500°C (932 °F), better than 90% of steel grades
- High strength — 700 MPa (102 ksi), better than 81% of steel grades
- Polishes to a fine finish — 65/100, better than 78% of steel grades
Limitations
- Difficult to weld — 15/100, worse than 91% of steel grades
- Limited formability — 18/100, worse than 84% of steel grades
- Poor heat conductor — 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades
41CrAlMo7-10 +QT650 properties
Typical room-temperature values for 41CrAlMo7-10 +QT650; 22 are specific to this condition. Other listed values are 41CrAlMo7-10 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
41CrAlMo7-10 +QT650 has a density of 7.75 g/cm³ (0.28 lb/in³), lighter than 93% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
41CrAlMo7-10 +QT650 has a yield strength of 700 MPa (102 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 81% of steel grades. Elongation at break is 15% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
41CrAlMo7-10 +QT650 is rated for continuous service to 500°C (932 °F). It conducts heat at 34 W/m·K (19.6 BTU/hr·ft·°F), worse than 77% of steel grades. Thermal expansion is 11.5 µm/m·K (6.39 µin/in·°F).
Electrical2
41CrAlMo7-10 +QT650 has an electrical resistivity of 2.5×10⁻⁷ Ω·m.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of 41CrAlMo7-10 +QT650 takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 30%.
Manufacturability8
41CrAlMo7-10 +QT650's machinability is fair (43/100, worse than 71% of steel grades); weldability poor (15/100); formability poor (18/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with 41CrAlMo7-10 +QT650
Is 41CrAlMo7-10 easy to machine?
Machine fully in the +QT condition with coated carbide at moderate speed and rigid setups; leave only 0.05–0.10 mm grinding stock because the nitrided case cannot be heavily removed.
Can 41CrAlMo7-10 be welded?
Essentially not weldable in service condition — high carbon plus ~1 % Al gives hard, crack-prone HAZ; if unavoidable use high preheat, matching low-hydrogen filler and immediate stress relief.
Can 41CrAlMo7-10 be formed, bent or molded?
Hot forge 1100–850 °C followed by slow cooling and soft annealing; cold forming is impractical at 300+ HB.
What surface finishes work on 41CrAlMo7-10?
Stress-relieve at ~30 °C below the tempering temperature before nitriding at 500–530 °C; mask non-nitrided areas with copper or paste, then oil, phosphate or blacken for corrosion protection (no anodising).
41CrAlMo7-10 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 | 0.38 – 0.45 | 0.41 |
| Si | ≤ 0.4 | 0.25 |
| Mn | 0.4 – 0.7 | 0.55 |
| PEN 10085 max | ≤ 0.03 | — |
| S≤0.005 for special-quality nitriding stock | ≤ 0.04 | — |
| Cr | 1.5 – 1.8 | 1.65 |
| Mo | 0.25 – 0.35 | 0.3 |
| Alforms hard AlN in the nitrided case | 0.8 – 1.2 | 1 |
| Fe | balance | — |
41CrAlMo7-10 +QT650 — frequently asked
What is 41CrAlMo7-10 +QT650 used for?
41CrAlMo7-10 +QT650 is typically used for heavy-duty gears, worm shafts, hydraulic components and extruder barrels. In short: deep-case nitriding steel; stronger core than 34CrAlMo5; 500 °C service capability.
What is the yield strength of 41CrAlMo7-10 +QT650?
41CrAlMo7-10 +QT650 has a typical yield strength of 700 MPa (102 ksi) and a tensile strength of 950 MPa (138 ksi) — stronger than 81% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is 41CrAlMo7-10 +QT650 easy to machine?
Not especially — machinability is rated fair (43/100, worse than 71% of steel grades). Machine fully in the +QT condition with coated carbide at moderate speed and rigid setups; leave only 0.05–0.10 mm grinding stock because the nitrided case cannot be heavily removed.
Can 41CrAlMo7-10 +QT650 be welded?
Not readily — weldability is rated poor (15/100). Essentially not weldable in service condition — high carbon plus ~1 % Al gives hard, crack-prone HAZ; if unavoidable use high preheat, matching low-hydrogen filler and immediate stress relief.
What surface finishes work on 41CrAlMo7-10 +QT650?
Stress-relieve at ~30 °C below the tempering temperature before nitriding at 500–530 °C; mask non-nitrided areas with copper or paste, then oil, phosphate or blacken for corrosion protection (no anodising).
Can 41CrAlMo7-10 +QT650 be formed, bent or molded?
Hot forge 1100–850 °C followed by slow cooling and soft annealing; cold forming is impractical at 300+ HB.
What is the maximum service temperature of 41CrAlMo7-10 +QT650?
41CrAlMo7-10 +QT650 is rated for continuous use to about 500°C (932 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- EN 10085 — Nitriding steels, technical delivery conditions — CEN (2001)
- GB/T 3077 — Alloy structural steels (38CrMoAlA) — SAC (2015)
- Nitriding steel 1.8509 / 41CrAlMo7-10 data sheet — Böhler / Deutsche Edelstahlwerke (2022)
- ASM Handbook Vol.4A — Steel Heat Treating / Nitriding — ASM International (2013)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
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.