E355 precision steel tube: properties by delivery condition, equivalents
E355 (1.0580) is the high-strength precision tube of EN 10305-1. Its properties depend entirely on the delivery condition: +N, +SR or +C. Table, hydraulic cylinder use and equivalents.
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What is E355?
E355 is the high-strength member of EN 10305-1, the European standard for seamless cold drawn precision tube, and material number 1.0580 — the same number the old German grade St 52 carried, which is why most enquiries for this tube still arrive written that way.
The thing that distinguishes a precision tube from every other tube on this site is what the standard actually guarantees. EN 10217 and EN 10216 promise wall integrity and leak-tightness: they are pressure specifications. EN 10305-1 promises dimensions and surface — close tolerances on outside diameter, wall thickness and straightness, plus specified inside and outside roughness, which no pressure standard mentions. A precision tube is bought so that a piston can run in it, a bearing can press into it, or a part can be machined from it with minimal stock.
That leads to the point this page exists to make. E355 has no single set of mechanical properties. The delivery condition decides them, and the spread is enormous:
+N (normalised) — 355 MPa minimum yield, 490–630 MPa tensile, 22 % elongation. The same figures as S355 plate, because it is essentially the same steel in the same condition.
+SR (cold drawn, stress relieved) — around 450 MPa yield, 580 MPa minimum tensile, 10 % elongation. The usual condition for hydraulic cylinders: most of the cold-work strength kept, the drawing stresses relieved so the tube does not move when it is machined.
+C (cold drawn, hard) — 640 MPa minimum tensile, 4 % elongation, and no specified yield strength at all. Strong, dimensionally exact, and with almost no ductility left.
So a drawing that says only "E355" has not specified the tube. It must say E355+N, E355+SR or E355+C, and a certificate without the suffix is incomplete. Where no yield value is given, the published practice is to assume at least 80 % of the tensile for the hard condition and 70 % for the soft — a recommendation rather than a guarantee, and a reminder that this is a dimensional standard first.
E355 chemical composition
| Element | Mass % | Note |
|---|---|---|
| C | ≤ 0.22 | |
| Si | ≤ 0.55 | |
| Mn | ≤ 1.6 | |
| P | ≤ 0.025 | |
| S | ≤ 0.025 |
EN 10305-1, grade E355 (1.0580). The analysis is essentially that of S355J2 — and indeed 1.0580 is the material number shared with the old St 52 family — which is why E355 tube and S355 plate behave alike once the tube is normalised. The leaner grades in the same standard are E215, E235 and E275; E470 sits above.
E355 mechanical properties
| Thickness / condition | Yield strength ReH / Rp0.2 MPa (ksi) | Tensile strength Rm MPa (ksi) | Elongation A % | Hardness |
|---|---|---|---|---|
| +N normalised | ≥ 355 (≥ 51.5) | 490–630 (71.1–91.4) | 22 | — |
| +SR cold drawn, stress relieved | ≈ 450 (≈ 65.3) | ≥ 580 (≥ 84.1) | 10 | — |
| +C cold drawn, hard | not specified (≈ 80 % of Rm) (not specified (≈ 11.6 % of Rm)) | ≥ 640 (≥ 92.8) | 4 | — |
| E235+N — for comparison | ≥ 235 (≥ 34.1) | 340–480 (49.3–69.6) | 25 | — |
| E235+C — for comparison | not specified (not specified) | ≥ 480 (≥ 69.6) | 4 | — |
| +A and +LC conditions | — | — | — | see the standard's table — intermediate between +N and +SR |
**Read the suffix before the grade.** A single E355 tube can be delivered at 490 MPa tensile with 22 % elongation or at 640 MPa with 4 %, depending only on whether it was normalised or left cold-drawn hard, and the yield strength is **not stated at all** for the hard condition. Published practice where no yield is given is to take **≥ 80 % of the tensile strength for the hard condition and ≥ 70 % for the soft**, but that is a recommendation, not a specified value — which matters because EN 10305-1 is a *dimensional* standard first. Supplier tables also differ slightly on the +SR yield (435 or 450 MPa is quoted); take the figure from the current standard or the certificate.
E355 equivalent grades
| Grade | System | Match | Why / differences |
|---|---|---|---|
| a519-1026 | ASTM / ASME | Near | ASTM A519 grade 1026 seamless mechanical tubing: the nearest North American counterpart — mechanical rather than pressure tubing, supplied cold drawn or normalised, with properties stated by condition in the same way. A513 covers the welded mechanical equivalent. |
| St52-3 | DIN (superseded German) | Near | The withdrawn DIN name and the one still used in the shop for this tube — St 52.4 for the cold-finished precision tube, St 52.0 for the seamless pressure tube, both material number 1.0580. The caution is the same as on the St 52 page: St 52-3 as a *structural* grade corresponds to S355J2, not to S355JR, and the tube grades are specified differently again. |
| S355J2 | EN (European) | Near | EN 10025-2 S355J2: effectively the same analysis and, in the +N condition, the same 355 MPa yield and 490–630 MPa tensile. The difference is what else each standard demands — S355J2 guarantees 27 J at −20 °C and structural tolerances, while E355 guarantees dimensional precision and surface finish and requires no impact test at all. |
| E470 | EN (European) | Near | The strongest grade of EN 10305-1, used where a hydraulic cylinder wall must be thinner. Less formable and harder to machine; E355 is the normal choice. |
| E235 | EN (European) | Near | The general-purpose precision tube at 235 MPa yield in the +N condition. Easier to bend and form; the usual choice for fuel and brake lines, furniture and light mechanical work where E355 is specified for pressure-bearing cylinders. |
| STKM 13C | JIS (Japan) | Near | JIS G3445 STKM 13C: carbon steel tube for machine structural purposes, cold drawn, 510 MPa minimum tensile. The JIS series likewise splits each grade by delivery condition with suffixes A, B and C. |
| P235TR1 | EN (European) | Functional | EN 10217-1 P235TR1: the welded pressure tube at 235 MPa yield. A pressure tube is specified for leak-tightness and wall integrity; a precision tube is specified for dimensions and finish. Neither substitutes for the other, and a precision tube should not be used as a pressure-retaining part without checking the design code. |
| E250 | IS (India) | Functional | Listed only as the Indian structural reference point; India specifies mechanical tube to IS 3601 and IS 4923, not to a precision-tube standard of this kind. |
Identical = same composition and mechanical limits within rounding. Near = one limit differs (e.g. carbon max or impact temperature). Functional = interchangeable for most uses after an engineering check. Full cross-reference for E355 →
Old and superseded designations
| Old name | Standard | Note |
|---|---|---|
| St 52.4 / St 52.0 | DIN 2391-2 / DIN 1629 (withdrawn) | The German precision and seamless tube grades E355 descends from, sharing material number 1.0580. Still the common shop name for this tube across Germany, Turkey and Poland, and the reason E355 enquiries so often arrive written as "St 52 tube". |
| St 35 / St 45 | DIN 2391 (withdrawn) | The lower grades of the same family, now E235 and E275. |
| CFS 4 / CDS 4 | BS 6323 Part 4 (withdrawn) | The British cold-finished seamless tube grades of comparable strength. |
| TU 52b | NF A 49-310 | The French precision tube designation. |
Product forms and tolerance standards
Product forms: seamless cold drawn tube (EN 10305-1), welded cold drawn tube (EN 10305-2) and as-welded (EN 10305-3), honed and skived-roller-burnished hydraulic cylinder tube (EN 10305-4), delivery conditions +C, +LC, +SR, +A, +N.
Dimensional tolerances: close dimensional tolerances on outside diameter, wall thickness and straightness are the purpose of the standard and are tabulated by condition — much tighter than EN 10216 or EN 10217; inside and outside surface roughness is specified, which no pressure-tube standard does; hydraulic cylinder tube: EN 10305-4 adds honed-bore tolerance classes and bore roughness.
Key property values
E355 properties by delivery condition
+N normalised: ReH ≥ 355 MPa, Rm 490–630 MPa, A ≥ 22 %. +SR cold drawn and stress relieved: ReH ≈ 450 MPa, Rm ≥ 580 MPa, A ≥ 10 %. +C cold drawn hard: Rm ≥ 640 MPa, A ≥ 4 %, yield not specified. +A annealed and +LC lightly cold worked sit between +N and +SR and are tabulated in the standard. The condition is part of the grade designation, not an afterthought — note that supplier tables differ slightly on the +SR yield (435 or 450 MPa), so the certificate or the current standard is the authority.
What the E number means
The minimum yield strength in MPa in the normalised condition — E355+N is 355 MPa yield, the same level as S355. This is read wrongly as often as it is read correctly, usually because the cold-finished conditions have far higher tensile strengths (640 MPa for +C) with no stated yield, so the number appears not to match anything on the certificate. The E prefix follows EN 10027-1 for engineering steels, exactly as S follows it for structural and P for pressure.
Why +SR is the hydraulic cylinder condition
A cold-drawn tube carries large residual stresses from drawing. Machine a keyway, a port or a flange seat into it and those stresses redistribute — the tube bends, the bore goes oval, and the cylinder leaks. +SR relieves them at around 550–620 °C while keeping most of the cold-work strength: 580 MPa tensile against 490 for +N, with 10 % elongation still available for the end forming. That combination of dimensional stability and strength is why EN 10305-4 cylinder tube is normally E355+SR, and why a cylinder maker will not accept +C.
Precision tube against pressure tube
Different standards answering different questions, and they are not interchangeable. EN 10305-1 guarantees outside diameter, wall thickness, straightness, inside and outside roughness — and tests nothing for pressure. EN 10216-1 / EN 10217-1 guarantee a leak test, weld integrity and in the TR2 qualities an impact test, with generous dimensional tolerances. A hydraulic cylinder needs the first; a pressure-retaining pipework component needs the second. Using a precision tube as a pressure part — common in practice because it is available and strong — is a decision for the design code, not for the stockist.
Forming, bending and end work
Strongly condition dependent. +N bends and expands freely: mandrel bending to 2–3 D, flaring, beading and swaging all routine. +SR bends to larger radii, typically 3–4 D, and tolerates moderate expansion. +C should be treated as unformable — 4 % elongation leaves nothing for a bend, and attempting one cracks the tube. The practical rule: choose the condition from the most demanding operation the tube must survive, not from the strength the finished part needs.
Machining and surface
Machinability around 65–70 % relative to 1 % C free-cutting steel in +N, somewhat better in the cold-drawn conditions where the harder surface gives cleaner chips. The attraction is the stock allowance: a precision tube's bore and outside diameter are close enough to finished size that many parts need only a light cut, and honed EN 10305-4 tube needs none at all on the bore. Cut a +C tube and expect movement; cut a +SR tube and it stays where it was put. Welding a cold-drawn tube locally anneals it and destroys the dimensional precision over several diameters, which is why precision tube assemblies are pressed, bolted or welded at the ends only.
Weldability
Weldable at this carbon level — the carbon equivalent runs around 0.35–0.45, so arc welding with E7018 or ER70S-6 needs no preheat in normal wall thickness, and the +N condition welds like S355. The caution is not metallurgical but dimensional: welding a cold-drawn tube locally anneals it and relieves its residual stresses unevenly, so the bore distorts for several diameters either side of the joint and the precision the tube was bought for is lost. Precision tube assemblies are therefore welded at the ends, outside the working length, or joined by pressing and threading. For a hydraulic cylinder, welding on the working length of a honed tube is not done.
Machining, forming and heat treatment
The reason the grade exists: close outside diameter and wall tolerances and specified surface roughness mean a part can be finished with a single light pass, and an EN 10305-4 honed tube needs no bore machining at all. Machinability about 65–70 % relative to 1 % C free-cutting steel in the normalised condition. The decisive point is residual stress — a +C tube moves when metal is removed from one side, while a +SR tube holds its shape, so any tube that will be slotted, ported, keyed or heavily turned should be ordered +SR or +N. Parting, drilling and cross-boring are straightforward. Keep clamping forces moderate on thin wall: a precision tube is easy to distort in a three-jaw chuck.
Typical applications
- Hydraulic and pneumatic cylinder barrels (usually E355+SR, honed to EN 10305-4)
- Hydraulic lines and high-pressure piping on mobile machinery
- Shock absorber and gas spring tubes
- Machined components made from tube — bushes, spacers, housings, rollers
- Bearing housings and press-fit sleeves
- Drive shafts, torque tubes and telescopic sections
- Machine frames and precision structures where tolerance matters more than strength
Frequently asked questions
What is the difference between E355+N, E355+SR and E355+C?
The delivery condition, and it changes the properties completely. +N (normalised) gives 355 MPa minimum yield, 490–630 MPa tensile and 22 % elongation. +SR (cold drawn and stress relieved) gives about 450 MPa yield, 580 MPa minimum tensile and 10 % elongation. +C (cold drawn hard) gives 640 MPa minimum tensile, only 4 % elongation, and no specified yield at all. A drawing that says just "E355" has not specified the tube.
Does the 355 in E355 mean tensile or yield strength?
Yield — the minimum yield strength in MPa in the normalised condition, following EN 10027-1 just as S does for structural and P for pressure grades. It is misread as tensile because the cold-finished conditions have much higher tensile strengths (640 MPa for +C) and often no stated yield, so the number appears not to match the certificate.
Is E355 the same as St 52?
It is the successor. The precision tube St 52.4 to DIN 2391-2 and the seamless tube St 52.0 to DIN 1629 both carried material number 1.0580, which E355 kept, and the analysis is essentially unchanged. The name St 52 is still in daily use for this tube. Note that St 52-3 as a *structural* grade is a different specification lineage and corresponds to S355J2.
Which condition should a hydraulic cylinder tube be?
E355+SR, honed or skived-and-roller-burnished to EN 10305-4. Cold drawing leaves residual stresses that make the bore distort when ports and mountings are machined; the stress-relief anneal removes them while keeping most of the cold-work strength — 580 MPa tensile with 10 % elongation still available for end forming. A +C tube is strong but will move during machining, and cylinder makers do not accept it.
Can E355 precision tube be used as a pressure pipe?
Not without the design code's agreement. EN 10305-1 guarantees dimensions and surface finish and contains no leak test, no weld integrity requirement and no impact test; those belong to EN 10216-1 and EN 10217-1, the seamless and welded pressure tube standards. E355 is widely used for high-pressure hydraulic lines, but that is done inside hydraulic design rules, not as a substitution for a pressure-tube specification in pipework.
What is the yield strength of E355+C?
The standard does not state one. Where a yield value is needed and none is specified, the published recommendation is to take at least 80 % of the tensile strength for the hard condition and 70 % for the soft — about 510 MPa for a 640 MPa +C tube. That is a recommendation rather than a guaranteed value, and if the design depends on it, order +SR or +N where the yield is specified.
Can E355 be bent?
It depends on the condition. +N bends freely, to 2–3 diameters on a mandrel, and tolerates flaring and swaging. +SR needs larger radii, typically 3–4 diameters. +C should be treated as unformable: 4 % elongation leaves nothing for a bend and the tube cracks. Choose the condition from the most demanding operation the tube has to survive, not from the strength the finished part needs.
What is the ASTM equivalent of E355?
ASTM A519 grade 1026 seamless mechanical tubing is the nearest, with A513 covering the welded equivalent. Both are mechanical rather than pressure tubing and, like EN 10305-1, state properties by delivery condition. JIS G3445 STKM 13C is the Japanese counterpart. None is a drop-in substitute, because the dimensional tolerance tables and surface requirements differ.
Related grades
Verified against EN 10305-1:2016 (+N values); +SR and +C from supplier tables to EN 10305-1 — confirm against the current standard; EN 10305-1:2016 — seamless cold drawn precision steel tubes; EN 10305-4 (hydraulic cylinder tube); DIN 2391-2 (St 52.4 comparison); ASTM A519 (grade 1026 comparison). Last checked: October 2026.