Steel EN41B
BS EN41B
EN41B is a British Standard chromium-aluminium-molybdenum nitriding steel, equivalent to 34CrAlMo5, 38CrMoAl and 41CrAlMo7-10, in which the aluminium content forms a very hard, wear-resistant nitride case.
Values for the Q&T condition
EN41B tempers and conditions
EN41B is supplied in 6 conditions, soft to hard. Q&T is the default FabDigit quotes; the values on this page are for it.
Compare all 6 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
soft, spheroidised/full anneal for machining | Choose for rough machining or deep drilling of blanks before hardening and nitriding. | 450 | 700 | 20 | 200 HB | — |
air cooled from ~900 °C | Use for uniform grain size and stress relief on hot-worked bar prior to hardening. | 560 | 830 | 17 | 22 HRC | 8 % IACS |
Q&TDefault Quenched and tempered | Standard stocked condition: tough core ready for finish machining and subsequent nitriding. | 740 | 925 | 15 | 27 HRC | — |
Q&T + gas/plasma nitrided | The service condition for EN41B: use where extreme surface hardness, scuff and wear resistance with minimal distortion are needed. | 740 | 925 | 14 | 68 HRC | — |
Q&T condition U | Pick when a stronger core is needed under the nitrided case, e.g. highly loaded shafts. | 820 | 1,000 | 13 | 31 HRC | 7.8 % IACS |
Q&T condition V | Highest normally supplied core strength; accept reduced toughness and harder machining. | 880 | 1,075 | 11 | 33 HRC | 7.8 % IACS |
What is EN41B?
EN41B is a British Standard chromium-aluminium-molybdenum nitriding steel, equivalent to 34CrAlMo5, 38CrMoAl and 41CrAlMo7-10, in which the aluminium content forms a very hard, wear-resistant nitride case. Engineers specify it in the quenched-and-tempered condition (740 MPa yield, 925 MPa tensile, 15 % elongation, 269 HB / 27 HRC) as bar or forged blanks for shafts, screws and spindles that are finish-machined and then gas nitrided to 900-1100 HV. Service temperature is limited to about 450 °C and the steel is effectively non-weldable because of its 0.4 % C and 1.1 % Al content; corrosion resistance is low, so a coating or oil film is still required. Nitrided 42CrMo4 is the usual alternative where a lower case hardness is acceptable. EN41B 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). EN41B 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).
What is EN41B used for?
- Nitrided industrial shafts
- Gear surfaces and gear shafts
- Plastic extruder screws and barrels
- Machine tool spindles
- Pump shafts
- Valve stems
- Hydraulic piston rods
- Wear-resistant guide bushings
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 properties
Typical room-temperature values for EN41B-Q&T; bars are the position among steel grades.
Physical3
EN41B 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 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 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 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 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'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.
Strength versus weight in the steel family
Yield strength against density for every steel grade FabDigit runs. EN41B is highlighted; hover a dot for its name, or open the interactive family chart.
Working with EN41B
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.
Manufacturability
The process limits FabDigit applies to EN41B. Every EN41B part is priced by an engineer; design inside these and the quote comes back without a redesign loop.
CNC machining
| Machinability | Better50 / 100 |
|---|---|
| ISO material group | P.2 |
| Cutting speed (rough / finish) | 180 / 210 m/min |
| Minimum wall | 0.8 mm |
| Minimum internal radius | 1 mm |
| Drill depth limit | 5× diameter |
| Best surface (machined / polished) | Ra 1.6 / — |
| Hardenable after machining | No |
Sheet metal
| Formability | Fair25 / 100 |
|---|---|
| Weldability | Better20 / 100 |
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 |
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.
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).
Plating
CVD Coating
Black / Phosphate
Thermal Spray
Equivalent designations
Standards and trade names that resolve to Steel EN41B in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- BS
- 970 905M39
- Similar grades
- 34CrAlMo538CrMoAl41CrAlMo7-10
How much does EN41B cost?
EN41B is a standard-cost steel ($$), cheaper than about 71% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
EN41B — frequently asked
What is EN41B used for?
EN41B is typically used for nitrided industrial shafts, gear surfaces and gear shafts, plastic extruder screws and barrels, machine tool spindles, pump shafts and valve stems. In short: high-strength aerospace bar.
What is the yield strength of EN41B?
EN41B has a typical yield strength of 740 MPa (107 ksi) and a tensile strength of 925 MPa (134 ksi) — stronger than 83% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is EN41B easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines like a 30 HRC Cr-Mo steel — rigid setups, coated carbide, moderate speeds; finish-machine before nitriding and leave only 0.02–0.05 mm for lapping afterwards.
Can EN41B be welded?
Not readily — weldability is rated poor (20/100). Effectively non-weldable for structural joints (0.4 %C plus 1.1 %Al); if unavoidable, preheat 300–350 °C, use low-hydrogen consumables and post-weld temper, and never weld nitrided surfaces.
What surface finishes work on EN41B?
Gas or plasma nitride 500–530 °C for 900–1100 HV cases (0.2–0.6 mm); remove any brittle white layer by lapping, then oil, phosphate or black-oxide for corrosion protection.
Can EN41B be formed, bent or molded?
Hot forge 1050–1150 °C with slow cooling and a full anneal afterwards; cold forming is not practical in Q&T condition.
What is the maximum service temperature of EN41B?
EN41B is rated for continuous use to about 450°C (842 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does EN41B cost?
EN41B is a standard-cost steel ($$), cheaper than about 71% 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.
Can FabDigit make parts in EN41B?
Yes — EN41B is available for CNC machining and sheet metal; every part is priced by an engineer rather than instantly. 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; 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.