Steel EN41B · heat-treated state · default condition
Steel EN41B Q&T
Properties of the Q&T condition, compared with the other EN41B tempers.
Standard stocked condition: tough core ready for finish machining and subsequent nitriding.
What is EN41B Q&T?
EN41B Q&T is EN41B heat treated to Q&T — standard stocked condition: tough core ready for finish machining and subsequent nitriding. EN41B Q&T has a yield strength of 740 MPa (107 ksi) and a tensile strength of 925 MPa (134 ksi) — stronger than 83% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi). EN41B Q&T has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Advantages
- Polishes to a fine finish — 70/100, better than 87% of steel grades
- High service temperature — 450°C (842 °F), better than 86% of steel grades
- High strength — 740 MPa (107 ksi), better than 83% of steel grades
Limitations
- Difficult to weld — 20/100, worse than 84% of steel grades
EN41B Q&T properties
Typical room-temperature values for EN41B Q&T — 10 properties are specific to this condition; the rest are grade-level values shared by every EN41B temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
EN41B Q&T has a density of 7.8 g/cm³ (0.282 lb/in³), lighter than 87% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
EN41B Q&T has a yield strength of 740 MPa (107 ksi) and a tensile strength of 925 MPa (134 ksi) — stronger than 83% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
EN41B Q&T is rated for continuous service to 450°C (842 °F). It conducts heat at 40 W/m·K (23.1 BTU/hr·ft·°F), worse than 64% of steel grades. Thermal expansion is 12 µm/m·K (6.67 µin/in·°F).
Electrical2
EN41B Q&T has an electrical resistivity of 2.2×10⁻⁷ Ω·m.
Chemical & Environmental2
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of EN41B Q&T takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
EN41B Q&T's machinability is fair (50/100, worse than 53% of steel grades); weldability poor (20/100); formability poor (25/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other EN41B tempers and conditions
EN41B is also supplied in 5 other conditions. The full side-by-side table is on the EN41B overview.
- Q&TDefaultStandard stocked condition: tough core ready for finish machining and subsequent nitriding.740 MPa yield · 27 HRC
- Q&T-VHighest normally supplied core strength; accept reduced toughness and harder machining.880 MPa yield · 33 HRC
- Q&T-UPick when a stronger core is needed under the nitrided case, e.g. highly loaded shafts.820 MPa yield · 31 HRC
- Q&T+NitridedThe service condition for EN41B: use where extreme surface hardness, scuff and wear resistance with minimal distortion are needed.740 MPa yield · 68 HRC
- AnnealedChoose for rough machining or deep drilling of blanks before hardening and nitriding.450 MPa yield · 200 HB
Working with EN41B Q&T
Is EN41B easy to machine?
Machines like a 30 HRC Cr-Mo steel — rigid setups, coated carbide, moderate speeds; finish-machine before nitriding and leave only 0.02–0.05 mm for lapping afterwards.
Can EN41B be welded?
Effectively non-weldable for structural joints (0.4 %C plus 1.1 %Al); if unavoidable, preheat 300–350 °C, use low-hydrogen consumables and post-weld temper, and never weld nitrided surfaces.
Can EN41B be formed, bent or molded?
Hot forge 1050–1150 °C with slow cooling and a full anneal afterwards; cold forming is not practical in Q&T condition.
What surface finishes work on EN41B?
Gas or plasma nitride 500–530 °C for 900–1100 HV cases (0.2–0.6 mm); remove any brittle white layer by lapping, then oil, phosphate or black-oxide for corrosion protection.
EN41B 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 | 0.35 – 0.45 | 0.4 |
| Si | 0.1 – 0.4 | 0.25 |
| Mn | 0.4 – 0.65 | 0.55 |
| Cr | 1.4 – 1.8 | 1.6 |
| Mo | 0.15 – 0.25 | 0.2 |
| Alforms hard AlN-rich nitrided case | 0.9 – 1.3 | 1.1 |
| P0.05 max in older BS 970 issues | ≤ 0.04 | — |
| S0.05 max in older BS 970 issues | ≤ 0.04 | — |
| Fe | balance | — |
EN41B Q&T — frequently asked
What is EN41B Q&T used for?
EN41B Q&T is typically used for nitrided industrial shafts, gear surfaces and gear shafts, plastic extruder screws and barrels, machine tool spindles, pump shafts and valve stems. In short: high-strength aerospace bar.
What is the yield strength of EN41B Q&T?
EN41B Q&T has a typical yield strength of 740 MPa (107 ksi) and a tensile strength of 925 MPa (134 ksi) — stronger than 83% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is EN41B Q&T easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines like a 30 HRC Cr-Mo steel — rigid setups, coated carbide, moderate speeds; finish-machine before nitriding and leave only 0.02–0.05 mm for lapping afterwards.
Can EN41B Q&T be welded?
Not readily — weldability is rated poor (20/100). Effectively non-weldable for structural joints (0.4 %C plus 1.1 %Al); if unavoidable, preheat 300–350 °C, use low-hydrogen consumables and post-weld temper, and never weld nitrided surfaces.
What surface finishes work on EN41B Q&T?
Gas or plasma nitride 500–530 °C for 900–1100 HV cases (0.2–0.6 mm); remove any brittle white layer by lapping, then oil, phosphate or black-oxide for corrosion protection.
Can EN41B Q&T be formed, bent or molded?
Hot forge 1050–1150 °C with slow cooling and a full anneal afterwards; cold forming is not practical in Q&T condition.
What is the maximum service temperature of EN41B Q&T?
EN41B Q&T is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Can FabDigit make parts in EN41B Q&T?
Yes — EN41B Q&T is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- BS 970-3: Wrought steels — 905M39 (EN41B) — BSI (1991)
- GB/T 3077 — 38CrMoAlA — SAC (2015)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4A: Steel Heat Treating — Nitriding — ASM International (2013)
- Nitriding steel 905M39 / 1.8509-type bar datasheet — Special steel stockholders (2022)
- 38CrMoAlA — 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.