Steel En26-X (Q&T condition X)
Hardness band
For high-duty fasteners and aerospace-type parts where toughness can be traded for strength.
Values for the X condition
Other En26 tempers and conditions
En26 is listed in 9 conditions; see the grade overview at En26.
Compare all 9 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
fully softened for machining/forming | Pick for rough machining of large sections before hardening, or for cold forming. | 450 | 700 | 22 | 205 HB | — |
air cooled from ~870 °C | Use to refine grain and homogenise forgings prior to hardening; not a service condition for this grade. | 620 | 950 | 14 | 29 HRC | 7.3 % IACS |
TDefault Q&T condition T | Most commonly stocked bar condition — best toughness/strength balance for shafts and general engineering. | 730 | 930 | 16 | 28 HRC | — |
Q&T + gas nitrided case | Choose when a wear-resistant, fatigue-strengthening surface is needed on a tough core with negligible distortion. | 790 | 1,000 | 12 | 60 HRC | 7.2 % IACS |
Q&T condition V | Common for medium-large gears and heavily loaded shafts. | 850 | 1,075 | 14 | 34 HRC | — |
Solution heat treated (unstable) | High-strength condition for compact, heavily stressed shafts and pins. | 940 | 1,150 | 13 | 36 HRC | — |
XThis page Q&T condition X | For high-duty fasteners and aerospace-type parts where toughness can be traded for strength. | 1,030 | 1,225 | 12 | 40 HRC | — |
Q&T condition Y | Very high strength; specify only where impact loading is limited and stress raisers are controlled. | 1,100 | 1,310 | 11 | 42 HRC | — |
Q&T condition Z | Maximum-strength low-temperature-tempered condition for small sections; low toughness and hydrogen-embrittlement sensitive. | 1,350 | 1,620 | 8 | 49 HRC | — |
What is En26-X?
En26-X is En26 heat treated to X — for high-duty fasteners and aerospace-type parts where toughness can be traded for strength. En26-X has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,225 MPa (178 ksi) — stronger than 93% of steel grades. Elongation at break is 12% and the elastic modulus is 207 GPa (30 Msi). En26-X has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F). T is the default condition FabDigit quotes; X is available on request or by drawing note.
Advantages
- High strength — 1,030 MPa (149 ksi), better than 93% of steel grades
- Polishes to a fine finish — 70/100, better than 87% of steel grades
Limitations
- Limited ductility — 12%, worse than 84% of steel grades
- Difficult to weld — 25/100, worse than 77% of steel grades
En26-X properties
Typical room-temperature values for En26-X; 11 are specific to this condition. Other listed values are En26 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
En26-X has a density of 7.83 g/cm³ (0.283 lb/in³), lighter than 80% of steel grades. It melts at 1,420°C (2,588 °F).
Mechanical16
En26-X has a yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,225 MPa (178 ksi) — stronger than 93% of steel grades. Elongation at break is 12% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
En26-X is rated for continuous service to 320°C (608 °F). It conducts heat at 43 W/m·K (24.8 BTU/hr·ft·°F), better than 51% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
En26-X conducts electricity at 7.2 % IACS, worse than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of En26-X takes about 34 MJ of energy and emits 2.4 kg of CO₂ — more than 82% of steel grades. Typical recycled content is 25%.
Manufacturability8
En26-X's machinability is fair (45/100, worse than 65% of steel grades); weldability poor (25/100); formability poor (25/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with En26-X
Is En26 easy to machine?
Machine in annealed or condition T/U with rigid setups, sharp carbide and generous coolant; above ~350 HB expect low tool life — consider grinding or finish-machining before final temper.
Can En26 be welded?
Poor weldability (CE ≈ 0.9): preheat 250–350 °C, low-hydrogen electrodes, and immediate post-weld temper below the original tempering temperature; avoid welding in conditions X/Y/Z.
Can En26 be formed, bent or molded?
Hot forge 1150–850 °C then slow cool/anneal; cold forming only in the annealed state with generous bend radii.
What surface finishes work on En26?
Not anodisable — protect with zinc/cadmium plating (bake at 190–200 °C to relieve hydrogen), black oxide, phosphate + oil, or nitride for wear surfaces; polishes to a fine finish when hardened.
En26 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 |
| P | ≤ 0.04 | — |
| Smax; 826M40 free-cutting variants allow 0.15–0.25 S | ≤ 0.04 | — |
| Ni | 2.3 – 2.8 | 2.55 |
| Cr | 0.5 – 0.8 | 0.65 |
| Mo | 0.45 – 0.65 | 0.55 |
| Fe | balance | — |
En26-X — frequently asked
What is En26-X used for?
En26-X is typically used for large shafts, gears, crankshafts and aerospace fasteners. In short: highest-hardenability En Ni-Cr-Mo; stronger alternative to En25; poor weldability, CE ≈ 0.9.
What is the yield strength of En26-X?
En26-X has a typical yield strength of 1,030 MPa (149 ksi) and a tensile strength of 1,225 MPa (178 ksi) — stronger than 93% of steel grades. Strength varies by condition: see the 9 listed tempers.
Is En26-X easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 65% of steel grades). Machine in annealed or condition T/U with rigid setups, sharp carbide and generous coolant; above ~350 HB expect low tool life — consider grinding or finish-machining before final temper.
Can En26-X be welded?
Not readily — weldability is rated poor (25/100). Poor weldability (CE ≈ 0.9): preheat 250–350 °C, low-hydrogen electrodes, and immediate post-weld temper below the original tempering temperature; avoid welding in conditions X/Y/Z.
What surface finishes work on En26-X?
Not anodisable — protect with zinc/cadmium plating (bake at 190–200 °C to relieve hydrogen), black oxide, phosphate + oil, or nitride for wear surfaces; polishes to a fine finish when hardened.
Can En26-X be formed, bent or molded?
Hot forge 1150–850 °C then slow cool/anneal; cold forming only in the annealed state with generous bend radii.
What is the maximum service temperature of En26-X?
En26-X is rated for continuous use to about 320°C (608 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between En26-T and En26-Z?
T is the default condition — most commonly stocked bar condition — best toughness/strength balance for shafts and general engineering. Z: maximum-strength low-temperature-tempered condition for small sections; low toughness and hydrogen-embrittlement sensitive. Yield strength is 730 MPa in T versus 1,350 MPa in Z.
Sources
- BS 970-1: Wrought steels — 826M40 (En26) — BSI (1991)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol.19 — Fatigue and Fracture — ASM International (1996)
- MMPDS — 4340 low-alloy steel design allowables — Battelle/FAA (2022)
- GB/T 3077 — 40CrNiMoA (2015)
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.