EN 10305-1 E235 Honed Seamless Steel Tube For Hydraulic Overview
Sep 21, 2026
EN 10305-1 E235 honed seamless steel tube for hydraulic cylinders is a low-carbon cold-drawn precision tube whose inner bore is finished by honing to ISO H8 with surface roughness Ra ≤ 0.4 µm (16 µin), so the piston seal runs directly on the tube wall. Supplied stress-relieved (+SR) at ID 40–300 mm (1.6–11.8 in) and wall 5–40 mm (0.20–1.57 in), it reaches the cylinder with no secondary boring required. The property that decides cylinder life is not the steel name but the bore geometry - tolerance, texture and straightness together.
E235 is the EN 10305-1 name for a low-carbon non-alloy steel (St 35, material number 1.0308); the tube is made from hot-finished seamless stock by cold drawing, then honed. We stock and cut to length with EN 10204 3.1 certificates and third-party inspection on request. Send your ID × OD × wall, Ra and destination port for a quote.
Technical Specifications
| Parameter | Capability |
|---|---|
| Standard | EN 10305-1:2016 (seamless cold-drawn precision tube) |
| Grade | E235 (St 35, material no. 1.0308), low-carbon non-alloy |
| Inner diameter (honed) | 40–300 mm (1.6–11.8 in); larger on request |
| Wall thickness | 5–40 mm (0.20–1.57 in) |
| Length | Up to 12 m (39 ft) fixed, or random 5–7 m |
| Bore tolerance | ISO H8 (H7/H9/H10 available) |
| Inner roughness | Ra ≤ 0.4 µm (Ra 0.2 µm by SRB) |
| Straightness | ≤ 0.5 mm/m |
| Delivery condition | +SR (stress relieved) standard; +N, +A, +C on request |
| Surface option | Oiled; hard chrome plating on request |
| Certification | EN 10204 3.1; third-party inspection available |
Chemical Composition
| Element | E235 (max unless noted) |
|---|---|
| Carbon (C) | ≤ 0.17 |
| Silicon (Si) | ≤ 0.35 |
| Manganese (Mn) | ≤ 1.20 |
| Phosphorus (P) | ≤ 0.025 |
| Sulfur (S) | ≤ 0.025 |
| Aluminium total (Al), if fully killed | ≥ 0.015 |
Carbon is capped at 0.17 % so the tube stays low-carbon - weldable and formable. Tight P and S limits protect ductility and surface quality, which matter because the bore is the finished sealing face.
Mechanical Properties
| Condition | Tensile Rm (MPa) | Yield ReH (MPa) | Elongation A (%) |
|---|---|---|---|
| +C (cold drawn hard) | ≥ 480 | ≈ 0.8 × Rm | ≥ 6 |
| +LC (cold drawn soft) | ≥ 420 | > 0.7 × Rm | ≥ 10 |
| +SR (stress relieved) | ≥ 420 | ≥ 350 | ≥ 16 |
| +A (annealed) | ≥ 315 | ≈ 0.5 × Rm | ≥ 25 |
| +N (normalized) | 340–480 | ≥ 235 | ≥ 25 |
The yield is set by the condition, not the grade. That is why a cylinder barrel is normally ordered in +SR: it holds ≥ 350 MPa while keeping residual stress low enough that the bore stays true through honing and service. Quoting only "E235 235 MPa" undersells the tube by a full strength class.
Choosing the Delivery Condition
| Condition | Yield (MPa) | Use it when |
|---|---|---|
| +SR (stress relieved) | ≥ 350 | Default for honed cylinder barrels - stable bore, high strength |
| +N (normalized) | ≥ 235 | You need maximum ductility or softer machining; accept lower yield |
| +C (cold drawn hard) | ≈ 0.8 × 480 | Machined sleeves that are not heavily formed; not for tight-bore stability |
| +A (annealed) | ≈ 0.5 × 315 | Severe bending or end forming after supply |
ID Tolerance Grade Selection
| Grade | Fit | Trade-off | Typical use |
|---|---|---|---|
| H8 | Standard | Best all-round cost/performance | Most hydraulic cylinder barrels |
| H9 | Looser | Cheaper, faster; more seal clearance | Low-pressure or non-critical cylinders |
| H7 | Tighter | Costs more; less clearance | High-precision or high-speed cylinders |
State the grade. Leaving it open usually returns H8, which is right for most barrels but not all.
Why Source E235 Honed Tube from GNEE
Certified and traceable. EN 10204 3.1 certificates with heat-number traceability; third-party inspection arranged on request.
Grade-ladder coverage. E235 and E355 honed tubes from one source, so you step up the grade without changing supplier.
Engineering support. We confirm the delivery condition and bore grade against your seal and pressure before quoting, not after.
Flexible finish. Oiled or hard chrome plated, with cut-to-length and export packaging.
How to Specify Your Order
Standard and grade - EN 10305-1 E235.
Inner diameter × outer diameter × wall (state all three; ID alone is not enough).
Bore tolerance grade - H8 (H7/H9/H10 if different).
Required inner roughness - Ra ≤ 0.4 µm (or Ra 0.2 µm by SRB).
Delivery condition - +SR (stress relieved) unless another is needed.
Length and quantity - fixed up to 12 m, or random.
Surface option - oiled, or hard chrome plating with thickness.
Certificate - EN 10204 3.1; third-party inspection and scope.
Destination port and required lead time.
Test and inspection
Packaging and shipping
Send your inner diameter × outer diameter × wall, bore tolerance grade, required Ra and destination port - our technical team confirms the delivery condition and returns a quotation with lead time, usually within 24 hours.
Request an E235 Honed Tube Quote
FAQ
What is an EN 10305-1 E235 honed tube used for?
It is the finished barrel of a hydraulic cylinder. The tube is supplied with a honed inner bore (ISO H8, Ra ≤ 0.4 µm) so the piston seal runs directly on the tube wall without further machining. E235 is the low-carbon default grade for light- to medium-duty cylinders; step up to E355 when the same wall carries a higher pressure.
Is E235 the same as St 35?
Yes. E235, St 35 and material number 1.0308 are the same steel under different naming systems - E235 is the current EN 10305-1 designation, St 35 is the legacy DIN 2391 name. The chemistry (C ≤ 0.17 %, Mn ≤ 1.20 %) and the normalized yield of 235 MPa are identical.
Why does E235 show two different yield strengths?
Because the yield depends on the delivery condition, not the grade name alone. Normalized (+N) E235 has a defined yield of ≥ 235 MPa; stress-relieved (+SR) reaches ≥ 350 MPa; cold-drawn hard (+C) can reach about 0.8 × 480 ≈ 384 MPa. Specifying the condition is what fixes the number - omitting it lets the mill default to +N.
What ID tolerance and surface finish does a hydraulic honed tube have?
The honed bore is supplied to ISO H8 as standard (H7, H9 or H10 available on request), with surface roughness Ra ≤ 0.4 µm and straightness ≤ 0.5 mm/m. Skived and roller-burnished (SRB) tubes can reach Ra 0.2 µm. These values are what let the seal seat without a secondary machining pass.
Should I specify +SR or +N for a cylinder barrel?
Specify +SR (stress relieved) for honed cylinder barrels in most cases: it holds the ≥ 350 MPa yield while keeping residual stress low so the bore stays stable during honing and in service. Choose +N (normalized, yield ≥ 235 MPa) only when you need maximum ductility or softer machinability; +C is for machined sleeves that are not heavily formed.
Is a honed tube the same as an SRB tube?
Both are finished cylinder bores but by different methods. Honing is low-force abrasive cutting that corrects geometry; skiving and roller burnishing (SRB) plastically deforms the surface, giving higher throughput and often Ra 0.2 µm. They are not interchangeable on every seal design, so the bore finish should follow the seal manufacturer's Ra and texture guidance.
Can an E235 honed tube be hard chrome plated?
Yes. Hard chrome plating is a common add-on for piston-side cylinders that need wear and corrosion resistance, applied after honing to a specified plating thickness. State the plating thickness and any post-plate honing requirement when you order; it is a surface option, not part of the EN 10305-1 base tube.
How do I specify an E235 honed tube order?
Give: standard and grade (EN 10305-1 E235), inner diameter × outer diameter × wall, length and quantity, bore tolerance grade (H8/H9), required Ra, delivery condition (+SR preferred), any chrome plating, certificate level (EN 10204 3.1), and destination port. Send these and we return a quote with lead time.
