Steel EN41B · hardness band
Steel EN41B Q&T-U
Properties of the Q&T-U condition, compared with the other EN41B tempers.
Pick when a stronger core is needed under the nitrided case, e.g. highly loaded shafts.
What is EN41B Q&T-U?
EN41B Q&T-U is EN41B heat treated to Q&T-U — pick when a stronger core is needed under the nitrided case, e.g. highly loaded shafts. EN41B Q&T-U has a yield strength of 820 MPa (119 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 87% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi). EN41B Q&T-U 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). Q&T is the default condition FabDigit quotes; Q&T-U is available on request or by drawing note.
Advantages
- High strength — 820 MPa (119 ksi), better than 87% of steel grades
- 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
Limitations
- Difficult to weld — 20/100, worse than 84% of steel grades
- Limited ductility — 13%, worse than 78% of steel grades
EN41B Q&T-U properties
Typical room-temperature values for EN41B Q&T-U — 9 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-U 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-U has a yield strength of 820 MPa (119 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 87% of steel grades. Elongation at break is 13% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
EN41B Q&T-U 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-U 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-U 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-U's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (20/100); formability poor (25/100).
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-U
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-U — frequently asked
What is EN41B Q&T-U used for?
EN41B Q&T-U 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-U?
EN41B Q&T-U has a typical yield strength of 820 MPa (119 ksi) and a tensile strength of 1,000 MPa (145 ksi) — stronger than 87% of steel grades. Strength varies by condition: see the 6 listed tempers.
Is EN41B Q&T-U easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% 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-U 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-U?
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-U 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-U?
EN41B Q&T-U 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-U?
Yes — EN41B Q&T-U 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.