Steel EN353 · heat-treated state
Steel EN353-CH
Properties of the CH condition, compared with the other EN353 tempers.
The service condition for gears and pinions — hard wear-resistant case on a tough 30–42 HRC core.
What is EN353-CH?
EN353-CH is EN353 heat treated to CH — the service condition for gears and pinions — hard wear-resistant case on a tough 30–42 HRC core. EN353-CH has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 90% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi). EN353-CH 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; CH is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 80/100, better than 97% of steel grades
- High strength — 900 MPa (131 ksi), better than 90% of steel grades
Limitations
- Difficult to machine — 8/100, worse than 100% of steel grades
- Difficult to weld — 10/100, worse than 99% of steel grades
- Limited service temperature — 180°C (356 °F), worse than 98% of steel grades
- Limited ductility — 10%, worse than 91% of steel grades
EN353-CH properties
Typical room-temperature values for EN353-CH — 14 properties are specific to this condition; the rest are grade-level values shared by every EN353 temper. Each bar shows where the value sits among the steel grades in FabDigit's library — further right is higher.
Physical3
EN353-CH 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
EN353-CH has a yield strength of 900 MPa (131 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 90% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
EN353-CH is rated for continuous service to 180°C (356 °F). It conducts heat at 44 W/m·K (25.4 BTU/hr·ft·°F), better than 57% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
EN353-CH conducts electricity at 7.8 % IACS, worse than 58% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (12/100), worse than 53% of steel grades.
Sustainability4
Producing a kilogram of EN353-CH takes about 30 MJ of energy and emits 2.1 kg of CO₂ — more than 55% of steel grades. Typical recycled content is 25%.
Manufacturability7
EN353-CH's machinability is not recommended (8/100, worse than 100% of steel grades); weldability not recommended (10/100); formability fair (45/100).
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other EN353 tempers and conditions
EN353 is also supplied in 6 other conditions. The full side-by-side table is on the EN353 overview.
- HRDefaultStandard stocked condition for gear blanks and forging stock; machined then carburized.480 MPa yield · 229 HB
- CHThe service condition for gears and pinions — hard wear-resistant case on a tough 30–42 HRC core.900 MPa yield · 60 HRC
- Q&TDirect hardening without carburizing when a tough, uniformly strong shaft or fastener core is wanted.800 MPa yield · 32 HRC
- CDChoose for close size tolerance, bright finish and higher as-supplied strength on small-diameter bar.660 MPa yield · 250 HB
- NormalizedUse to refine grain and homogenize forgings before carburizing; uniform machining response.550 MPa yield · 240 HB
- AnnealedPick for deep machining, broaching, hobbing or cold forming before carburizing.400 MPa yield · 190 HB
Working with EN353-CH
Is EN353 easy to machine?
Machine fully in the annealed or normalized state with carbide tooling (~120–180 m/min); after carburizing only grinding, honing or CBN hard-turning is practical.
Can EN353 be welded?
Weldable only before carburizing — preheat 200–250 °C, low-hydrogen consumables, post-weld stress relief; welding a carburized case will crack it.
Can EN353 be formed, bent or molded?
Hot forge at 1100–1150 °C and normalize afterwards; cold forming is limited to gentle bends in the annealed condition.
What surface finishes work on EN353?
No natural corrosion resistance — protect with oil, phosphate, black oxide, zinc/manganese phosphate or plating; keep 0.1–0.3 mm grinding stock for post-carburizing distortion.
EN353 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 |
|---|---|---|
| Ccase-hardening carbon level | 0.14 – 0.2 | 0.17 |
| Si | 0.15 – 0.35 | 0.25 |
| Mn | 0.6 – 0.9 | 0.75 |
| P | ≤ 0.04 | — |
| S | ≤ 0.04 | — |
| Cr | 0.75 – 1.25 | 1 |
| Ni | 1 – 1.5 | 1.25 |
| Mo | 0.08 – 0.15 | 0.12 |
| Fe | balance | — |
EN353-CH — frequently asked
What is EN353-CH used for?
EN353-CH is typically used for gears, industrial drive shafts and pins. In short: premium carburizing alloy bar.
What is the yield strength of EN353-CH?
EN353-CH has a typical yield strength of 900 MPa (131 ksi) and a tensile strength of 1,150 MPa (167 ksi) — stronger than 90% of steel grades. Strength varies by condition: see the 7 listed tempers.
Is EN353-CH easy to machine?
Not especially — machinability is rated not recommended (8/100, worse than 100% of steel grades). Machine fully in the annealed or normalized state with carbide tooling (~120–180 m/min); after carburizing only grinding, honing or CBN hard-turning is practical.
Can EN353-CH be welded?
Not readily — weldability is rated not recommended (10/100). Weldable only before carburizing — preheat 200–250 °C, low-hydrogen consumables, post-weld stress relief; welding a carburized case will crack it.
What surface finishes work on EN353-CH?
No natural corrosion resistance — protect with oil, phosphate, black oxide, zinc/manganese phosphate or plating; keep 0.1–0.3 mm grinding stock for post-carburizing distortion.
Can EN353-CH be formed, bent or molded?
Hot forge at 1100–1150 °C and normalize afterwards; cold forming is limited to gentle bends in the annealed condition.
What is the maximum service temperature of EN353-CH?
EN353-CH 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 EN353-HR and EN353-CH?
HR is the default condition — standard stocked condition for gear blanks and forging stock; machined then carburized. CH: the service condition for gears and pinions — hard wear-resistant case on a tough 30–42 HRC core. Yield strength is 480 MPa in HR versus 900 MPa in CH.
Can FabDigit make parts in EN353-CH?
Yes — EN353-CH 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 970-3: Wrought steels — 815M17 case hardening steel — BSI (1991)
- GB/T 3077 (20CrNi2Mo) — SAC (2015)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels — ASM International (1990)
- ASM Handbook Vol.4 — Heat Treating (Carburizing) — ASM International (1991)
- Alloy carburizing bar steel datasheets (EN353 / 815M17 / 20CrNi2Mo) — Various bar producers (2023)
- SMM / Mysteel — SMM / Mysteel (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.