Steel EN24 Normalized
Heat-treated state
BS EN24 · AISI/SAE 4340
Uniform grain and high strength without quench distortion; usually followed by tempering for stock relief.
Values for the Normalized condition
Other EN24 tempers and conditions
EN24 is listed in 12 conditions; see the grade overview at EN24.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
full/spheroidise annealed (condition A) | Softest condition for deep machining, cold forming or thread rolling before hardening. | 470 | 750 | 22 | 217 HB | — |
HRDefault Hot rolled | Cheapest raw stock for parts that will be heat treated after rough machining. | 520 | 850 | 15 | 22 HRC | — |
Cold rolled | Thin flat product with tight thickness and smooth surface; strength from cold work, heat treat after blanking. | 700 | 900 | 9 | 26 HRC | 7.8 % IACS |
Cold drawn | Bright, size-accurate bar for shafts machined to near-final size before hardening; best surface of the untreated forms. | 720 | 900 | 11 | 26 HRC | 7.8 % IACS |
Quenched and tempered | The standard stock condition (EN24T): best strength/toughness/machinability compromise for shafts, gears and general engineering parts. | 740 | 930 | 15 | 28 HRC | — |
Q&T condition U | One step above T when slightly higher strength is required with near-equal toughness. | 800 | 1,000 | 14 | 31 HRC | 7.8 % IACS |
NormalizedThis page austenitised ~860 °C, air cooled | Uniform grain and high strength without quench distortion; usually followed by tempering for stock relief. | 860 | 1,280 | 12 | 39 HRC | — |
Q&T condition V | Common for high-duty gears, torsion bars and heavy-duty shafting. | 900 | 1,080 | 13 | 34 HRC | 7.8 % IACS |
Q&T condition W | High-strength condition for aerospace/heavy machine parts; machining becomes noticeably harder. | 990 | 1,150 | 12 | 36 HRC | 7.7 % IACS |
Q&T condition X | Used where high yield strength dominates; watch notch sensitivity and plating hydrogen embrittlement. | 1,070 | 1,230 | 11 | 40 HRC | — |
Q&T condition Y | Near-top standard strength band for highly stressed bolts, rods and aerospace fittings. | 1,130 | 1,300 | 10 | 42 HRC | — |
Q&T condition Z | Maximum-strength condition for small sections and tooling; low ductility and high notch/hydrogen sensitivity. | 1,400 | 1,650 | 7 | 49 HRC | — |
What is EN24 Normalized?
EN24 Normalized is EN24 heat treated to Normalized — uniform grain and high strength without quench distortion; usually followed by tempering for stock relief. EN24 Normalized has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 89% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi). EN24 Normalized 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). HR is the default condition FabDigit quotes; Normalized is available on request or by drawing note.
Advantages
- High strength — 860 MPa (125 ksi), better than 89% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited formability — 15/100, worse than 87% of steel grades
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to machine — 40/100, worse than 77% of steel grades
EN24 Normalized properties
Typical room-temperature values for EN24 Normalized; 12 are specific to this condition. Other listed values are EN24 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
EN24 Normalized 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
EN24 Normalized has a yield strength of 860 MPa (125 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 89% of steel grades. Elongation at break is 12% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
EN24 Normalized is rated for continuous service to 400°C (752 °F). It conducts heat at 42 W/m·K (24.3 BTU/hr·ft·°F), worse than 56% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
EN24 Normalized conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (15/100), better than 75% of steel grades.
Sustainability4
Producing a kilogram of EN24 Normalized takes about 34 MJ of energy and emits 2.3 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 30%.
Manufacturability8
EN24 Normalized's machinability is fair (40/100, worse than 77% of steel grades); weldability poor (30/100); formability poor (15/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with EN24 Normalized
Is EN24 easy to machine?
Machinable at 248–302 HB with rigid setups, carbide tooling and generous coolant; above ~350 HB use coated carbide/CBN, low feeds and consider grinding for finishing.
Can EN24 be welded?
Restricted weldability — preheat 250–350 °C, low-hydrogen consumables (or matching Ni-Cr-Mo filler), and temper immediately after welding; cracking risk high in the hardened conditions.
Can EN24 be formed, bent or molded?
Hot forge 1150–850 °C then normalise or anneal; cold forming only in the annealed condition and limited to gentle bends.
What surface finishes work on EN24?
No anodising; protect by black oxide, phosphating, zinc or hard chrome plating, nitriding for surface wear — bake plated parts above 1000 MPa strength to relieve hydrogen.
EN24 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 | 0.36 – 0.44 | 0.4 |
| Si | 0.1 – 0.4 | 0.25 |
| Mn | 0.45 – 0.7 | 0.58 |
| Ni | 1.3 – 1.7 | 1.5 |
| Cr | 1 – 1.4 | 1.2 |
| Mo | 0.2 – 0.35 | 0.27 |
| S0.015–0.040 for 817M40; 0.050 max for free-machining 816M40 variant | ≤ 0.04 | 0.02 |
| P | ≤ 0.04 | 0.02 |
| Fe | balance |
EN24 Normalized — frequently asked
What is EN24 Normalized used for?
EN24 Normalized is typically used for drive shafts, industrial axles and forgings. In short: workhorse Q&T English bar.
What is the yield strength of EN24 Normalized?
EN24 Normalized has a typical yield strength of 860 MPa (125 ksi) and a tensile strength of 1,280 MPa (186 ksi) — stronger than 89% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is EN24 Normalized easy to machine?
Not especially — machinability is rated fair (40/100, worse than 77% of steel grades). Machinable at 248–302 HB with rigid setups, carbide tooling and generous coolant; above ~350 HB use coated carbide/CBN, low feeds and consider grinding for finishing.
Can EN24 Normalized be welded?
Not readily — weldability is rated poor (30/100). Restricted weldability — preheat 250–350 °C, low-hydrogen consumables (or matching Ni-Cr-Mo filler), and temper immediately after welding; cracking risk high in the hardened conditions.
What surface finishes work on EN24 Normalized?
No anodising; protect by black oxide, phosphating, zinc or hard chrome plating, nitriding for surface wear — bake plated parts above 1000 MPa strength to relieve hydrogen.
Can EN24 Normalized be formed, bent or molded?
Hot forge 1150–850 °C then normalise or anneal; cold forming only in the annealed condition and limited to gentle bends.
What is the maximum service temperature of EN24 Normalized?
EN24 Normalized is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between EN24-HR and EN24-CD?
HR is the default condition — cheapest raw stock for parts that will be heat treated after rough machining. CD: bright, size-accurate bar for shafts machined to near-final size before hardening; best surface of the untreated forms. Yield strength is 520 MPa in HR versus 720 MPa in CD.
Can FabDigit make parts in EN24 Normalized?
Yes — EN24 Normalized 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 970-1: Wrought steels — 817M40 (EN24) — BSI (1991)
- GB/T 3077 Alloy structural steels — 40CrNiMoA — SAC (2015)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels (AISI 4340) — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- MMPDS-17 typical properties, 4340 steel — Battelle/FAA (2022)
- EN24T / 817M40 hardened & tempered bar datasheets — West Yorkshire Steel / Interlloy (2023)
- 40CrNiMoA — Mysteel / 1688 (2026)
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.