Steel EN9 · hardness band
Steel EN9 Q&T-HH
Properties of the Q&T-HH condition, compared with the other EN9 tempers.
Pick when wear resistance and hardness (≈45–55 HRC) matter more than toughness, e.g. keys, wedges, small tooling.
What is EN9 Q&T-HH?
EN9 Q&T-HH is EN9 heat treated to Q&T-HH — pick when wear resistance and hardness (≈45–55 HRC) matter more than toughness, e.g. keys, wedges, small tooling. EN9 Q&T-HH has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 94% of steel grades. Elongation at break is 8% and the elastic modulus is 207 GPa (30 Msi). EN9 Q&T-HH 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; Q&T-HH is available on request or by drawing note.
Advantages
- High strength — 1,150 MPa (167 ksi), better than 94% of steel grades
- Conducts heat well — 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades
- High electrical conductivity — 10 % IACS, better than 82% of steel grades
Limitations
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 8%, worse than 95% of steel grades
EN9 Q&T-HH properties
Typical room-temperature values for EN9 Q&T-HH — 8 properties are specific to this condition; the rest are grade-level values shared by every EN9 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
EN9 Q&T-HH 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).
Mechanical14
EN9 Q&T-HH has a yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 94% of steel grades. Elongation at break is 8% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
EN9 Q&T-HH is rated for continuous service to 180°C (356 °F). It conducts heat at 49 W/m·K (28.3 BTU/hr·ft·°F), better than 83% of steel grades. Thermal expansion is 11.7 µm/m·K (6.5 µin/in·°F).
Electrical3
EN9 Q&T-HH conducts electricity at 10 % IACS, better than 82% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 87% of steel grades.
Sustainability4
Producing a kilogram of EN9 Q&T-HH takes about 25 MJ of energy and emits 2 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability7
EN9 Q&T-HH's machinability is fair (50/100, worse than 53% of steel grades); weldability fair (35/100); formability fair (35/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other EN9 tempers and conditions
EN9 is also supplied in 7 other conditions. The full side-by-side table is on the EN9 overview.
- HRDefaultStandard mill stock for shafting and general machined parts that will be heat treated later or used as-is at moderate load.340 MPa yield · 187 HB
- Q&T-HHPick when wear resistance and hardness (≈45–55 HRC) matter more than toughness, e.g. keys, wedges, small tooling.1,150 MPa yield · 50 HRC
- CDUse for close-tolerance, bright-finish bar where higher yield and better surface than hot rolled are wanted without heat treatment.570 MPa yield · 217 HB
- Q&TStandard condition for loaded shafts, gears and spindles needing a tough, uniform 200–255 HB core.540 MPa yield · 23 HRC
- NormalizedChoose for uniform fine pearlitic structure, refined grain and repeatable machining/heat-treat response.380 MPa yield · 200 HB
- AnnealedPick for maximum machinability, deep cold forming or before re-hardening.310 MPa yield · 170 HB
Working with EN9 Q&T-HH
Is EN9 easy to machine?
Machines cleanly in the annealed or normalized state (~55 % of AISI 1212); use rigid setups, carbide at 120–180 m/min, and expect tool life to fall sharply above ~250 HB.
Can EN9 be welded?
Poor weldability at 0.55 % C — preheat 200–300 °C, low-hydrogen consumables, and temper or slow-cool after welding to avoid martensitic cracking in the HAZ.
Can EN9 be formed, bent or molded?
Cold form only in the annealed condition with generous bend radii; hot forge at 1050–1200 °C and normalize afterwards to restore grain size.
What surface finishes work on EN9?
No inherent corrosion protection — oil, phosphate, black oxide, zinc plate or paint; takes a good ground/polished finish and is well suited to hard chrome on journals.
EN9 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 |
|---|---|---|
| CBS 970 070M55; suppliers quoting EN9 as 080M40 use 0.36–0.44 % C | 0.5 – 0.6 | 0.55 |
| Si | 0.05 – 0.35 | 0.2 |
| Mn | 0.5 – 0.9 | 0.7 |
| S | ≤ 0.06 | 0.03 |
| P | ≤ 0.06 | 0.03 |
| Fe | balance | — |
EN9 Q&T-HH — frequently asked
What is EN9 Q&T-HH used for?
EN9 Q&T-HH is typically used for crankshafts, shafts and industrial bolts. In short: medium-carbon English bar.
What is the yield strength of EN9 Q&T-HH?
EN9 Q&T-HH has a typical yield strength of 1,150 MPa (167 ksi) and a tensile strength of 1,500 MPa (218 ksi) — stronger than 94% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is EN9 Q&T-HH easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machines cleanly in the annealed or normalized state (~55 % of AISI 1212); use rigid setups, carbide at 120–180 m/min, and expect tool life to fall sharply above ~250 HB.
Can EN9 Q&T-HH be welded?
With care — weldability is rated fair (35/100). Poor weldability at 0.55 % C — preheat 200–300 °C, low-hydrogen consumables, and temper or slow-cool after welding to avoid martensitic cracking in the HAZ.
What surface finishes work on EN9 Q&T-HH?
No inherent corrosion protection — oil, phosphate, black oxide, zinc plate or paint; takes a good ground/polished finish and is well suited to hard chrome on journals.
Can EN9 Q&T-HH be formed, bent or molded?
Cold form only in the annealed condition with generous bend radii; hot forge at 1050–1200 °C and normalize afterwards to restore grain size.
What is the maximum service temperature of EN9 Q&T-HH?
EN9 Q&T-HH is rated for continuous use to about 180°C (356 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between EN9-HR and EN9-CR?
HR is the default condition — standard mill stock for shafting and general machined parts that will be heat treated later or used as-is at moderate load. CR: cold-rolled flat product for stamped springs, saw blades, blades and hardened flat components. Yield strength is 340 MPa in HR versus 600 MPa in CR.
Can FabDigit make parts in EN9 Q&T-HH?
Yes — EN9 Q&T-HH 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 970-1: Wrought steels for mechanical and allied engineering purposes (070M55 / En9) — BSI (1991)
- EN 10083-2 Steels for quenching and tempering — C55 — CEN (2006)
- ASM Handbook Vol.1: Properties and Selection — Irons, Steels and High-Performance Alloys — ASM International (1990)
- Machinery's Handbook (machinability ratings, heat treatment of carbon steels) — Industrial Press (2020)
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.