Steel E370 +AR (Hot rolled)
Heat-treated state · default condition
EN E370
Standard stock condition for E370 bar; pick when parts are fully machined from oversize black bar.
Values for the +AR condition
Other E370 tempers and conditions
E370 is listed in 8 conditions; see the grade overview at E370.
Compare all 8 conditionsHide
| Condition · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness | Conductivity |
|---|---|---|---|---|---|---|
Annealed | Pick when maximum softness for cold forming, deep drilling or heavy cold heading is required before final heat treatment. | 310 | 560 | 20 | 165 HB | — |
Normalized | Choose for uniform fine-grained structure and better toughness/dimensional stability before machining or induction hardening. | 390 | 660 | 16 | 190 HB | — |
+ARDefaultThis page Hot rolled | Standard stock condition for E370 bar; pick when parts are fully machined from oversize black bar. | 400 | 720 | 10 | 210 HB | — |
Peeled / turned and straightened bar | Large-diameter alternative to cold drawn: hot-rolled properties with a clean, decarb-free turned surface and tight straightness. | 400 | 700 | 12 | 15 HRC | 9 % IACS |
Induction hardened | Use for wear surfaces on shafts and rails: hard case (~55 HRC) over a tough as-rolled or normalized core. | 400 | 720 | 8 | 55 HRC | 8.5 % IACS |
Cold drawn | Use for close-tolerance shafts and pins that need good surface finish and higher yield strength with minimal machining. | 620 | 800 | 7 | 22 HRC | — |
Quenched and tempered | Pick when higher strength with retained toughness is needed in small sections; hardenability is limited, so use ≤ ~40 mm diameter. | 620 | 850 | 14 | 25 HRC | — |
Quenched and tempered to a specified hardness band | Specify this band for gears, shafts and pins needing consistent strength and machinability after heat treatment. | 720 | 950 | 12 | 30 HRC | — |
What is E370 +AR?
E370 +AR is E370 heat treated to +AR — standard stock condition for E370 bar; pick when parts are fully machined from oversize black bar. E370 +AR has a yield strength of 400 MPa (58 ksi) and a tensile strength of 720 MPa (104 ksi) — weaker than 60% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi). E370 +AR 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).
Advantages
- Conducts heat well — 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades
Limitations
- Limited ductility — 10%, worse than 91% of steel grades
- Low fracture toughness — 50 MPa·√m (45.5 ksi·√in), worse than 86% of steel grades
E370 +AR properties
Typical room-temperature values for E370 +AR; 11 are specific to this condition. Other listed values are E370 reference data and may not represent this condition. Bars are the position among steel grades.
Physical3
E370 +AR 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
E370 +AR has a yield strength of 400 MPa (58 ksi) and a tensile strength of 720 MPa (104 ksi) — weaker than 60% of steel grades. Elongation at break is 10% and the elastic modulus is 210 GPa (30.5 Msi).
Thermal6
E370 +AR is rated for continuous service to 350°C (662 °F). It conducts heat at 48 W/m·K (27.7 BTU/hr·ft·°F), better than 79% of steel grades. Thermal expansion is 11.8 µm/m·K (6.56 µin/in·°F).
Electrical3
E370 +AR conducts electricity at 9 % IACS, better than 71% of steel grades.
Chemical & Environmental3
Corrosion resistance is not recommended (10/100), worse than 86% of steel grades.
Sustainability4
Producing a kilogram of E370 +AR takes about 25 MJ of energy and emits 2.1 kg of CO₂ — less than 82% of steel grades. Typical recycled content is 30%.
Manufacturability6
E370 +AR's machinability is fair (48/100, worse than 57% of steel grades); weldability poor (33/100); formability poor (30/100).
Common Calculations5
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with E370 +AR
Is E370 easy to machine?
Machines like 1045: use carbide at 120–200 m/min with coolant; normalize or Q&T first to avoid gummy pearlite/ferrite banding and to improve surface finish.
Can E370 be welded?
Restricted weldability (CE ≈ 0.55–0.65) — preheat 150–250 °C, use low-hydrogen consumables and post-weld stress relief at 550–650 °C.
Can E370 be formed, bent or molded?
Hot forge at 1100–850 °C; cold bending is limited (generous bend radii, anneal first for severe forming).
What surface finishes work on E370?
Not anodizable — protect with paint, phosphate + oil, zinc plating, blackening or hard chrome; surfaces can be induction hardened and ground.
E370 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 |
|---|---|---|
| Cnot fixed by the standard — grade is defined by mechanical properties; producers typically supply 0.40–0.50 %C | ≤ 0.55 | 0.45 |
| Sitypical producer analysis | ≤ 0.4 | 0.25 |
| Mntypical producer analysis | ≤ 1.1 | 0.75 |
| Pladle analysis limit for non-alloy engineering steels | ≤ 0.05 | 0.03 |
| Sladle analysis limit | ≤ 0.05 | 0.03 |
| Nladle analysis limit unless N-binding elements present | ≤ 0.01 | 0.01 |
| Fe | balance | — |
E370 +AR — frequently asked
What is E370 +AR used for?
E370 +AR is typically used for machine shafts and pins, levers and links, fasteners requiring higher strength and general mechanical components. In short: strength-classified carbon bar; stronger than mild steel; limited weldability, restricted forming.
What is the yield strength of E370 +AR?
E370 +AR has a typical yield strength of 400 MPa (58 ksi) and a tensile strength of 720 MPa (104 ksi) — weaker than 60% of steel grades. Strength varies by condition: see the 8 listed tempers.
Is E370 +AR easy to machine?
Reasonably — machinability is rated fair (48/100, worse than 57% of steel grades). Machines like 1045: use carbide at 120–200 m/min with coolant; normalize or Q&T first to avoid gummy pearlite/ferrite banding and to improve surface finish.
Can E370 +AR be welded?
Not readily — weldability is rated poor (33/100). Restricted weldability (CE ≈ 0.55–0.65) — preheat 150–250 °C, use low-hydrogen consumables and post-weld stress relief at 550–650 °C.
What surface finishes work on E370 +AR?
Not anodizable — protect with paint, phosphate + oil, zinc plating, blackening or hard chrome; surfaces can be induction hardened and ground.
Can E370 +AR be formed, bent or molded?
Hot forge at 1100–850 °C; cold bending is limited (generous bend radii, anneal first for severe forming).
What is the maximum service temperature of E370 +AR?
E370 +AR is rated for continuous use to about 350°C (662 °F). Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between E370 +AR and E370-IH?
+AR is the default condition — standard stock condition for E370 bar; pick when parts are fully machined from oversize black bar. IH: use for wear surfaces on shafts and rails: hard case (~55 HRC) over a tough as-rolled or normalized core. Yield strength is 400 MPa in +AR versus 400 MPa in IH.
Sources
- EN 10025-2 (non-alloy structural/engineering steels, E-series analogues E295/E335/E360) — CEN (2019)
- EN 10277 — Bright steel products, technical delivery conditions — CEN (2018)
- ASM Handbook Vol.1 — Properties and Selection: Irons, Steels and High-Performance Alloys — ASM International (1990)
- GB/T 699 (45 comparison 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.