Steel EN24T Nitrided
Finish state
BS EN24T · AISI/SAE 4340
Add when wear resistance and fatigue life of a Q&T core are needed without distortion from re-hardening.
Values for the Nitrided condition
Other EN24T tempers and conditions
EN24T is listed in 13 conditions; see the grade overview at EN24T.
Compare all 13 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
soft, spheroidised/full annealed for machining | Pick when the part must be heavily machined or cold worked before its own hardening cycle. | 460 | 700 | 22 | 210 HB | — |
HRDefault Hot rolled | Cheapest mill condition for parts that will be fully heat treated after rough machining. | 560 | 900 | 16 | 26 HRC | 7.8 % IACS |
Quenched and tempered | The standard stocked EN24T condition — best all-round strength/toughness balance and still machinable. | 750 | 930 | 17 | 29 HRC | — |
NitridedThis page Q&T + gas/plasma nitrided case | Add when wear resistance and fatigue life of a Q&T core are needed without distortion from re-hardening. | 750 | 930 | 15 | 55 HRC | 7.8 % IACS |
Cold rolled | Flat product with tight thickness and improved surface for machined plates and blanks. | 780 | 940 | 14 | 30 HRC | 7.8 % IACS |
Cold drawn | Choose for bright, straight, close-tolerance shafting that needs little finish machining. | 800 | 950 | 14 | 30 HRC | 7.8 % IACS |
air cooled from ~870 °C | Grain refinement before final hardening; this air-hardening grade comes out hard, so a subcritical temper is usually added. | 800 | 1,150 | 12 | 36 HRC | — |
Q&T Condition U | One step above T when slightly higher strength is needed with almost the same toughness. | 820 | 1,000 | 15 | 31 HRC | 7.8 % IACS |
Q&T Condition V | Typical for heavier-duty shafts, gears and high-tensile fasteners. | 900 | 1,075 | 14 | 34 HRC | — |
Q&T Condition W | High-strength condition for aircraft/heavy-vehicle components; machining becomes noticeably harder. | 1,000 | 1,150 | 13 | 36 HRC | — |
Q&T Condition X | Used where very high tensile strength is required and toughness/machinability can be traded away. | 1,070 | 1,230 | 12 | 40 HRC | — |
Q&T Condition Y | Near the practical strength ceiling for machined parts; grinding often replaces turning. | 1,150 | 1,300 | 11 | 42 HRC | — |
Q&T Condition Z | Maximum-strength low-temper condition for small sections only; low toughness and high hydrogen-embrittlement risk. | 1,320 | 1,600 | 8 | 48 HRC | — |
What is EN24T Nitrided?
EN24T Nitrided is EN24T supplied in the Nitrided condition — add when wear resistance and fatigue life of a Q&T core are needed without distortion from re-hardening. EN24T Nitrided has a yield strength of 750 MPa (109 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 84% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi). EN24T Nitrided has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F). HR is the default condition FabDigit quotes; Nitrided is available on request or by drawing note.
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 — 750 MPa (109 ksi), better than 84% of steel grades
Limitations
- Difficult to weld — 5/100, worse than 100% of steel grades
- Difficult to machine — 12/100, worse than 99% of steel grades
- Limited formability — 5/100, worse than 99% of steel grades
EN24T Nitrided properties
Typical room-temperature values for EN24T Nitrided; 22 are specific to this condition. Other listed values are EN24T reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
EN24T Nitrided has a density of 7.85 g/cm³ (0.284 lb/in³), heavier than 56% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
EN24T Nitrided has a yield strength of 750 MPa (109 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 84% of steel grades. Elongation at break is 15% and the elastic modulus is 205 GPa (29.7 Msi).
Thermal6
EN24T Nitrided is rated for continuous service to 450°C (842 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
EN24T Nitrided conducts electricity at 7.8 % IACS, worse than 57% of steel grades.
Chemical & Environmental3
Corrosion resistance is poor (20/100), better than 87% of steel grades.
Sustainability4
Producing a kilogram of EN24T Nitrided takes about 32 MJ of energy and emits 2.3 kg of CO₂ — more than 70% of steel grades. Typical recycled content is 35%.
Manufacturability7
EN24T Nitrided's machinability is not recommended (12/100, worse than 99% of steel grades); weldability not recommended (5/100); formability not recommended (5/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with EN24T Nitrided
Is EN24T easy to machine?
Machinable in T condition with carbide at ~90–140 m/min, rigid setups and positive rake; above ~350 HB switch to CBN/ceramic or grind.
Can EN24T be welded?
Poor weldability (CE ≈ 0.9–1.0): use low-hydrogen consumables, preheat 250–350 °C, interpass control and immediate PWHT/temper below the original tempering temperature.
Can EN24T be formed, bent or molded?
Hot forge 1100–1200 °C finishing above 900 °C then slow cool or normalise; cold forming is not practical in Q&T conditions.
What surface finishes work on EN24T?
Not anodizable — protect with zinc/nickel plating, black oxide, phosphate or paint; bake 190–210 °C after plating to avoid hydrogen embrittlement, or nitride for wear surfaces.
EN24T 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 – 0.35 | 0.25 |
| Mn | 0.45 – 0.7 | 0.6 |
| Ni | 1.3 – 1.7 | 1.5 |
| Cr | 1 – 1.4 | 1.2 |
| Mo | 0.2 – 0.35 | 0.28 |
| P | ≤ 0.04 | — |
| Smax; 817M40S variant is resulphurised for machinability | ≤ 0.04 | — |
| Fe | balance | — |
EN24T Nitrided — frequently asked
What is EN24T Nitrided used for?
EN24T Nitrided is typically used for drive shafts, forged industrial parts, gearbox shafts and pinions, high-strength bolts and studs, crankshafts and axles and torsion bars. In short: Q&T Ni-Cr-Mo bar.
What is the yield strength of EN24T Nitrided?
EN24T Nitrided has a typical yield strength of 750 MPa (109 ksi) and a tensile strength of 930 MPa (135 ksi) — stronger than 84% of steel grades. Strength varies by condition: see the 13 listed tempers.
Is EN24T Nitrided easy to machine?
Not especially — machinability is rated not recommended (12/100, worse than 99% of steel grades). Machinable in T condition with carbide at ~90–140 m/min, rigid setups and positive rake; above ~350 HB switch to CBN/ceramic or grind.
Can EN24T Nitrided be welded?
Not readily — weldability is rated not recommended (5/100). Poor weldability (CE ≈ 0.9–1.0): use low-hydrogen consumables, preheat 250–350 °C, interpass control and immediate PWHT/temper below the original tempering temperature.
What surface finishes work on EN24T Nitrided?
Not anodizable — protect with zinc/nickel plating, black oxide, phosphate or paint; bake 190–210 °C after plating to avoid hydrogen embrittlement, or nitride for wear surfaces.
Can EN24T Nitrided be formed, bent or molded?
Hot forge 1100–1200 °C finishing above 900 °C then slow cool or normalise; cold forming is not practical in Q&T conditions.
What is the maximum service temperature of EN24T Nitrided?
EN24T Nitrided 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.
What is the difference between EN24T-HR and EN24T-CD?
HR is the default condition — cheapest mill condition for parts that will be fully heat treated after rough machining. CD: choose for bright, straight, close-tolerance shafting that needs little finish machining. Yield strength is 560 MPa in HR versus 800 MPa in CD.
Can FabDigit make parts in EN24T Nitrided?
Yes — EN24T Nitrided 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) mechanical condition T–Z — BSI (1991)
- EN 10083-3 / GB/T 3077 — 40CrNiMoA (34CrNiMo6 family) alloy structural steel — CEN / SAC (2015)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys (4340) — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- Machinery's Handbook — machinability ratings — Industrial Press (2020)
- 817M40 / EN24T engineering steel datasheets — West Yorkshire Steel / Interlloy / Smiths Metal Centres (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.