Steel En18-HR (Hot rolled)
Supply condition
Cheapest stock form for parts that will be fully machined and heat treated afterwards.
Values for the HR condition
Other En18 tempers and conditions
En18 is listed in 12 conditions; see the grade overview at En18.
Compare all 12 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Solution annealed | Choose for maximum machinability and cold-working before final heat treatment. | 400 | 620 | 24 | 187 HB | — |
HRThis page Hot rolled | Cheapest stock form for parts that will be fully machined and heat treated afterwards. | 430 | 700 | 19 | 16 HRC | 7.9 % IACS |
Normalized | Use as a uniform, moderately strong starting condition for forgings before machining or final Q&T. | 460 | 730 | 20 | 17 HRC | 7.9 % IACS |
Q&T condition R | Lowest hardened-and-tempered class; use for large sections (limiting ruling section ~150 mm) needing toughness over strength. | 560 | 770 | 20 | 20 HRC | — |
Q&T condition S | General-purpose Q&T level for shafts and couplings up to about 100 mm ruling section. | 620 | 850 | 18 | 24 HRC | — |
Cold drawn | Pick for close size tolerance and good surface on shafts and studs used without further hardening. | 660 | 800 | 12 | 22 HRC | 7.8 % IACS |
TDefault Q&T condition T | Most commonly stocked hardened-and-tempered condition for En18 gear blanks, spindles and shafts up to ~63 mm ruling section. | 700 | 920 | 15 | 28 HRC | — |
Induction hardened | Select when a wear-resistant 50+ HRC case with tough Q&T core is needed on journals, gear teeth or splines. | 720 | 950 | 14 | 55 HRC | 7.5 % IACS |
Q&T to 28–32 HRC | Hardness-specified order equivalent to condition T; common for gear and shaft machining shops. | 740 | 950 | 15 | 30 HRC | 7.7 % IACS |
Q&T condition V | For small-section high-strength parts where toughness demands are moderate. | 840 | 1,075 | 12 | 34 HRC | 7.8 % IACS |
Solution heat treated (unstable) | Top strength class, only achievable in thin sections; check impact requirements before specifying. | 920 | 1,150 | 11 | 36 HRC | 7.7 % IACS |
Q&T to 34–38 HRC | Higher-hardness Q&T for wear-loaded small shafts and pins; machining becomes noticeably harder. | 930 | 1,150 | 11 | 36 HRC | 7.6 % IACS |
What is En18-HR?
En18-HR is En18 supplied in the HR condition — cheapest stock form for parts that will be fully machined and heat treated afterwards. En18-HR has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 51% of steel grades. Elongation at break is 19% and the elastic modulus is 207 GPa (30 Msi). En18-HR 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). T is the default condition FabDigit quotes; HR is available on request or by drawing note.
Advantages
- Polishes to a fine finish — 65/100, better than 78% of steel grades
En18-HR properties
Typical room-temperature values for En18-HR; 23 are specific to this condition. Other listed values are En18 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
En18-HR 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).
Mechanical16
En18-HR has a yield strength of 430 MPa (62.4 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 51% of steel grades. Elongation at break is 19% and the elastic modulus is 207 GPa (30 Msi).
Thermal6
En18-HR is rated for continuous service to 400°C (752 °F). It conducts heat at 44.5 W/m·K (25.7 BTU/hr·ft·°F), better than 63% of steel grades. Thermal expansion is 12.3 µm/m·K (6.83 µin/in·°F).
Electrical3
En18-HR conducts electricity at 7.9 % IACS, better than 50% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (11/100), worse than 73% of steel grades.
Sustainability4
Producing a kilogram of En18-HR takes about 33 MJ of energy and emits 2.1 kg of CO₂ — more than 76% of steel grades. Typical recycled content is 35%.
Manufacturability7
En18-HR's machinability is good (55/100, better than 62% of steel grades); weldability fair (42/100); formability poor (33/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with En18-HR
Is En18 easy to machine?
Machines well at 180–300 HB with carbide tooling and rigid setups; above ~34 HRC expect reduced tool life, so rough-machine before final tempering or use hard-turning inserts.
Can En18 be welded?
Weldable with care only — preheat 200–300 °C, low-hydrogen consumables and post-weld temper at 550–650 °C to avoid hard, crack-prone HAZ martensite.
Can En18 be formed, bent or molded?
Hot forge 1050–1200 °C then normalize or anneal; cold forming limited to mild bending in the annealed condition due to the 0.4 % C level.
What surface finishes work on En18?
No anodizing — protect with black oxide, phosphate, zinc or hard-chrome plating; nitriding or induction hardening can be added for wear surfaces, and the fine-grained structure polishes well.
En18 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 |
|---|---|---|
| CAISI 5140: 0.38–0.43 | 0.36 – 0.44 | 0.4 |
| Si | 0.1 – 0.4 | 0.25 |
| Mn530A40 0.60–0.90; 530M40 0.60–1.00; 5140 0.70–0.90 | 0.6 – 1 | 0.8 |
| CrAISI 5140: 0.70–0.90 | 0.9 – 1.2 | 1.05 |
| Smax; 530A40 may specify 0.015–0.040 | ≤ 0.04 | — |
| P | ≤ 0.04 | — |
| Fe | balance | — |
En18-HR — frequently asked
What is En18-HR used for?
En18-HR is typically used for gears, spindles, shafts and bolts. In short: BS equivalent of 5140; economical 1%Cr through-hardener; takes induction hardening well.
What is the yield strength of En18-HR?
En18-HR has a typical yield strength of 430 MPa (62.4 ksi) and a tensile strength of 700 MPa (102 ksi) — weaker than 51% of steel grades. Strength varies by condition: see the 12 listed tempers.
Is En18-HR easy to machine?
Reasonably — machinability is rated good (55/100, better than 62% of steel grades). Machines well at 180–300 HB with carbide tooling and rigid setups; above ~34 HRC expect reduced tool life, so rough-machine before final tempering or use hard-turning inserts.
Can En18-HR be welded?
With care — weldability is rated fair (42/100). Weldable with care only — preheat 200–300 °C, low-hydrogen consumables and post-weld temper at 550–650 °C to avoid hard, crack-prone HAZ martensite.
What surface finishes work on En18-HR?
No anodizing — protect with black oxide, phosphate, zinc or hard-chrome plating; nitriding or induction hardening can be added for wear surfaces, and the fine-grained structure polishes well.
Can En18-HR be formed, bent or molded?
Hot forge 1050–1200 °C then normalize or anneal; cold forming limited to mild bending in the annealed condition due to the 0.4 % C level.
What is the maximum service temperature of En18-HR?
En18-HR is rated for continuous use to about 400°C (752 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between En18-T and En18-A?
T is the default condition — most commonly stocked hardened-and-tempered condition for En18 gear blanks, spindles and shafts up to ~63 mm ruling section. A: choose for maximum machinability and cold-working before final heat treatment. Yield strength is 700 MPa in T versus 400 MPa in A.
Sources
- BS 970-1:1991 (530A40 / 530M40, formerly En18) — BSI (1991)
- SAE J404 / ASTM A29 – alloy steel 5140 — SAE / ASTM (2019)
- ASM Handbook Vol.1: Properties and Selection – Irons, Steels — ASM International (1990)
- ASM Handbook Vol.19: Fatigue and Fracture — ASM International (1996)
- Machinery's Handbook (machinability ratings, heat treatment data) — Industrial Press (2020)
- GB/T 3077 (40Cr equivalent grade) — SAC (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.