Steel En34-QT (Quenched and tempered)
Heat-treated state
Used when a tough medium-strength part is needed without a case, or to characterise the refined core of carburized components.
Values for the QT condition
Other En34 tempers and conditions
En34 is listed in 5 conditions; see the grade overview at En34.
Compare all 5 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for maximum softness before heavy machining, cold forming or deep upsetting of blanks that will later be carburized. | 300 | 500 | 28 | 150 HB | — |
NDefault Normalized | Standard stock condition for carburizing blanks: uniform fine grain, good machinability, core properties before case hardening. | 400 | 620 | 21 | 180 HB | — |
Cold drawn | Pick for close-tolerance bright bar for pins, spindles and screw-machine parts where the part is finished before case hardening. | 550 | 690 | 13 | 205 HB | — |
QTThis page Quenched and tempered | Used when a tough medium-strength part is needed without a case, or to characterise the refined core of carburized components. | 590 | 780 | 16 | 24 HRC | — |
Carburized and hardened | The service condition for gears, pins and cams: 0.5–1.5 mm hard case at ~58–62 HRC over a tough 250–320 HB nickel-steel core. | 600 | 800 | 13 | 60 HRC | — |
What is En34-QT?
En34-QT is En34 heat treated to QT — used when a tough medium-strength part is needed without a case, or to characterise the refined core of carburized components. En34-QT has a yield strength of 590 MPa (85.6 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 76% of steel grades. Elongation at break is 16% and the elastic modulus is 207 GPa (30 Msi). En34-QT 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). N is the default condition FabDigit quotes; QT is available on request or by drawing note.
Advantages
- High strength — 590 MPa (85.6 ksi), better than 76% of steel grades
Limitations
- Limited service temperature — 300°C (572 °F), worse than 78% of steel grades
En34-QT properties
Typical room-temperature values for En34-QT; 10 are specific to this condition. Other listed values are En34 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
En34-QT 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
En34-QT has a yield strength of 590 MPa (85.6 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 76% of steel grades. Elongation at break is 16% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
En34-QT is rated for continuous service to 300°C (572 °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 µm/m·K (6.67 µin/in·°F).
Electrical3
En34-QT conducts electricity at 8 % IACS, better than 55% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (13/100), better than 66% of steel grades.
Sustainability4
Producing a kilogram of En34-QT takes about 30 MJ of energy and emits 2.2 kg of CO₂ — more than 56% of steel grades. Typical recycled content is 30%.
Manufacturability7
En34-QT's machinability is fair (50/100, worse than 53% of steel grades); weldability good (62/100); formability good (58/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with En34-QT
Is En34 easy to machine?
Machine in the normalized or annealed state with carbide at 100–160 m/min; gummy chips respond well to sharp positive tooling and generous coolant — finish all cutting before carburizing, then grind.
Can En34 be welded?
Low carbon equivalent gives good arc weldability with low-hydrogen consumables and 100–150 °C preheat; never weld through a carburized case, and re-carburize or stress-relieve after welding.
Can En34 be formed, bent or molded?
Hot forge 1150–850 °C then normalize at 880–910 °C; annealed bar cold-heads and bends acceptably, cold-drawn bar needs generous bend radii.
What surface finishes work on En34?
No inherent corrosion resistance — protect with black oxide, phosphate + oil, zinc or nickel plating (bake to avoid hydrogen embrittlement after case hardening); hardened cases grind and polish to a fine bearing finish.
En34 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 |
|---|---|---|
| Clow carbon for a tough core prior to carburizing | 0.1 – 0.18 | 0.14 |
| Si | 0.1 – 0.35 | 0.25 |
| Mn | 0.35 – 0.75 | 0.55 |
| Ninickel is the principal alloying addition of the En34 type | 1.25 – 2 | 1.6 |
| Crresidual/optional in some mill practices | ≤ 0.3 | 0.15 |
| Mosmall Mo addition in Ni-Mo variants of this En number | ≤ 0.25 | 0.1 |
| S | ≤ 0.05 | 0.03 |
| P | ≤ 0.05 | 0.03 |
| Fe | balance | — |
En34-QT — frequently asked
What is En34-QT used for?
En34-QT is typically used for gears, pins and small shafts. In short: most machinable carburizing grade; weldable before case hardening; tough core, light duty.
What is the yield strength of En34-QT?
En34-QT has a typical yield strength of 590 MPa (85.6 ksi) and a tensile strength of 780 MPa (113 ksi) — stronger than 76% of steel grades. Strength varies by condition: see the 5 listed tempers.
Is En34-QT easy to machine?
Reasonably — machinability is rated fair (50/100, worse than 53% of steel grades). Machine in the normalized or annealed state with carbide at 100–160 m/min; gummy chips respond well to sharp positive tooling and generous coolant — finish all cutting before carburizing, then grind.
Can En34-QT be welded?
Yes — weldability is rated good (62/100). Low carbon equivalent gives good arc weldability with low-hydrogen consumables and 100–150 °C preheat; never weld through a carburized case, and re-carburize or stress-relieve after welding.
What surface finishes work on En34-QT?
No inherent corrosion resistance — protect with black oxide, phosphate + oil, zinc or nickel plating (bake to avoid hydrogen embrittlement after case hardening); hardened cases grind and polish to a fine bearing finish.
Can En34-QT be formed, bent or molded?
Hot forge 1150–850 °C then normalize at 880–910 °C; annealed bar cold-heads and bends acceptably, cold-drawn bar needs generous bend radii.
What is the maximum service temperature of En34-QT?
En34-QT is rated for continuous use to about 300°C (572 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between En34-N and En34-CH?
N is the default condition — standard stock condition for carburizing blanks: uniform fine grain, good machinability, core properties before case hardening. CH: the service condition for gears, pins and cams: 0.5–1.5 mm hard case at ~58–62 HRC over a tough 250–320 HB nickel-steel core. Yield strength is 400 MPa in N versus 600 MPa in CH.
Sources
- BS 970: Wrought steels for mechanical and allied engineering purposes (En-series / Part 3 case-hardening steels) — BSI (1991)
- Handbook of Comparative World Steel Standards — ASTM International (2016)
- ASM Handbook Vol. 1 — Properties and Selection: Irons, Steels, and High-Performance Alloys — ASM International (1990)
- ASM Handbook Vol. 4 — Heat Treating (carburizing and case hardening) — ASM International (1991)
- 20CrNi/20CrMnTi — Mysteel (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.