DIN 2391 St52 Cold Drawn Steel Tube
DIN 2391 St52 cold drawn steel tube is a non-alloy carbon-manganese precision tube with a 355 MPa minimum yield and 490–630 MPa tensile range, made from the same steel as EN 10305-1 E355 (material number 1.0580). It is a cold-drawn seamless tube, not a welded pipe, and it is a German/European grade - there is no "ASTM St52." This page covers the numbers you need to order and the mistakes to avoid when a supplier writes the name.
The DIN 2391 St52 tube is the workhorse of hydraulic cylinders, automotive components and precision machinery because it combines tight tolerances with predictable weldability. GNEE supplies it in every delivery condition and in the normalized (NBK) condition most engineers design to. Send your OD × wall × length and delivery condition for a quote.
Technical Specifications
The DIN 2391 St52 dimensions below define the standard production envelope; larger outside diameters, walls and lengths are available on request.
| Parameter | Capability |
|---|---|
| Standard | DIN 2391 (precision seamless); EN 10305-1 E355; DIN 1629 / EN 10216-3 for structural seamless |
| Grade | St52 (material number 1.0580); EN 10305-1 E355 |
| Outside diameter | 4–260 mm (0.16–10.2 in) |
| Wall thickness | 0.5–25 mm (0.02–0.98 in) |
| Length | Fixed 3–12 m (9.8–39.4 ft); random lengths on request |
| Delivery condition | BK, BKW, BKS, GBK, NBK (+N) |
| Ends | Plain ends; beveled on request |
| Surface | Bright annealed, pickled, or honed/SRB bore |
| Certification | EN 10204 3.1 mill certificate; third-party inspection available |
St52 Chemical Composition
| Element | St52 / E355 (DIN 2391) | Note |
|---|---|---|
| Carbon (C) | ≤0.22% | Low carbon for weldability |
| Silicon (Si) | ≤0.55% | Deoxidation |
| Manganese (Mn) | ≤1.60% | Raises strength |
| Phosphorus (P) | ≤0.025% | Precision-tube limit (tighter than structural 0.035%) |
| Sulfur (S) | ≤0.025% | Precision-tube limit (tighter than structural 0.035%) |
The phosphorus and sulfur limits are the precision-tube values from DIN 2391. The structural standard EN 10025-2 allows up to 0.035%; using the looser number on a precision tube is a common error.
St52 Mechanical Properties
St52 yield strength 355 MPa is the minimum in the normalized or annealed condition; tensile stays in the 490–630 MPa band. The value you read on a certificate depends on the delivery condition, which is why some sources quote higher numbers.
| Delivery condition | Tensile Rm (MPa) | Yield Rp0.2 (MPa, min) | Elongation A5 (%) |
|---|---|---|---|
| BK (cold finished, hard) | ≥640 | - | ≥4 |
| BKW (cold finished, soft) | 600–750 | ≥355 | ≥16 |
| BKS (stress relieved) | 640–790 | ≥450 | ≥14 |
| GBK (annealed) | 490–630 | ≥355 | ≥20 |
| NBK (normalized, +N) | 490–630 | ≥355 | ≥22 |
Design to the NBK/GBK figures (490–630 MPa tensile, ≥355 MPa yield). The 600–790 MPa tensile quoted by some suppliers is the cold-worked BKW/BKS value, not the standard reference.
St52 Delivery Conditions (BK, BKW, BKS, GBK, NBK)
Choosing the St52 delivery condition BK BKW BKS NBK (with GBK as the soft annealed option) sets how the tube is heat-treated after drawing and therefore which strength row applies.
| Code | Meaning | When to choose |
|---|---|---|
| BK | Cold finished, no heat treatment after drawing | Maximum strength, low ductility; not for forming |
| BKW | Cold finished, light final draw | Moderate forming with good strength |
| BKS | Cold finished, stress relieved | After machining to reduce distortion |
| GBK | Annealed (soft) | Heavy cold forming, bending |
| NBK (+N) | Normalized, uniform structure | Default for cylinders and structural use |
Dimensional Tolerances
A St52 cold drawn tube tolerance is far tighter than a hot-finished tube. For outside diameter up to 30 mm the tolerance is about ±0.08 mm to ±0.15 mm; wall thickness is held to ±10% or ±0.10 mm, whichever is larger. Straightness is ≤1 mm per metre. These are the figures that let the tube drop into a cylinder without re-machining.
St52 Equivalent Grade and Near-Alternatives
| Region / standard | Equivalent | Use note |
|---|---|---|
| EU, precision tube | EN 10305-1 E355 (1.0580) | Same steel, current EU name |
| EU, structural | EN 10025-2 S355JR / S355J2 | Sections and plate; J2 adds −20 °C impact |
| USA, mechanical tubing | ASTM A519 Grade 1026 | Closest US mechanical-tube grade |
| USA, structural | ASTM A500 Grade C / A572 Grade 50 | Structural substitute, 345 MPa yield |
| China | GB/T 1591 Q355B (legacy Q345B) | National near-equivalent |
Pick the equivalent by the standard your project references. If the drawing says "St52," you can accept EN 10305-1 E355 or, for US projects, specify St52 equivalent ASTM A519 1026 and confirm the delivery condition in writing.
Seamless vs Welded Precision Tube
| Route | Standard | Best for |
|---|---|---|
| Seamless cold drawn | DIN 2391 / EN 10305-1 | Hydraulic bores, high-pressure cylinders |
| Welded cold drawn | DIN 2393 / EN 10305-2 | Lower-cost non-critical precision tube |
Both meet the same grade, but only the seamless route carries no longitudinal weld - specify which one you need.
Quality Control and Testing
Dimensional check - OD, wall, straightness and length verified per DIN 2391 limits.
Surface inspection - bore and OD checked for scratches, scale and decarburization.
Non-destructive testing - eddy current (ET) as standard; ultrasonic (UT) on request for thicker walls.
Mechanical verification - tensile, yield and elongation from the heat, reported on the 3.1 certificate.
Third-party inspection - SGS, BV or client-appointed surveyor available before shipment.
Packaging and shipping
Send your outside diameter × wall thickness, length, delivery condition (NBK by default) and destination port - our technical team will confirm the specification and return a quotation with lead time within 24 hours. Contact GNEE Pipe today.
Why Source DIN 2391 St52 Tube from GNEE
As a DIN 2391 St52 tube supplier and St52 cold drawn tube manufacturer, GNEE ships St52/E355 in every delivery condition with EN 10204 3.1 certification and supports inspection, cutting and export documentation end to end.
Mill-direct supply of DIN 2391 St52 and EN 10305-1 E355 in BK/BKW/BKS/GBK/NBK.
Full traceability from heat number to 3.1 certificate; third-party inspection on request.
Cut-to-length, custom OD/wall, and bore finishing (honed or SRB) available.
Export experience to 160+ customers across Europe, the Middle East, Asia and the Americas.
FAQ
Is St52 an ASTM grade?
No. St52 is a German and European designation, not an ASTM grade. It comes from the withdrawn DIN 17100 structural standard and the DIN 2391 precision-tube standard; the current European names are EN 10305-1 E355 for precision tubes and EN 10025-2 S355 for structural sections. The closest ASTM equivalents are ASTM A519 Grade 1026 for mechanical tubing and ASTM A500 or A572 Grade 50 for structural tubing. There is no grade called 'ASTM St52'.
What is St52 steel?
St52 is a non-alloy carbon-manganese structural steel with a minimum yield strength of 355 MPa. 'St' means Stahl (steel) and '52' refers to the legacy 52 kgf/mm² class. As a cold-drawn precision tube it is supplied to DIN 2391 as grade St52 (material number 1.0580), which is the same steel as EN 10305-1 E355. It is not a stainless or alloy steel.
What is the equivalent of St52?
For precision tubes the equivalent is EN 10305-1 E355 (1.0580). For structural use the equivalent is EN 10025-2 S355JR or S355J2. In the United States the nearest mechanical-tubing grade is ASTM A519 Grade 1026, while ASTM A500 Grade C and ASTM A572 Grade 50 are structural substitutes. In China the closest grade is GB/T 1591 Q355B. Always confirm the exact standard and delivery condition on the order.
Why does St52 show two different strength values?
Because the strength depends on the delivery condition. In the normalized or annealed condition (NBK or GBK) St52 shows 490–630 MPa tensile and a minimum yield of 355 MPa. In the cold-worked conditions (BK, BKW, BKS) cold drawing raises the tensile to 600–790 MPa and yield to 355–450 MPa but reduces elongation. The reference value buyers should design to is the NBK/GBK figure of 490–630 MPa tensile and ≥355 MPa yield.
What are the St52 chemical composition limits?
For DIN 2391 precision tubes St52 is limited to Carbon ≤0.22%, Silicon ≤0.55%, Manganese ≤1.60%, Phosphorus ≤0.025% and Sulfur ≤0.025%. Note that structural grades to EN 10025-2 allow P and S up to 0.035%, so the tighter 0.025% limit applies to the precision-tube standard, not the structural standard.
What dimensions does DIN 2391 St52 cover?
DIN 2391 St52 cold drawn steel tube is typically produced from 4 mm to 260 mm outside diameter and 0.5 mm to 25 mm wall thickness, with fixed or random lengths up to about 12 m. Larger diameters and lengths are available on request. Outside-diameter tolerance is in the ±0.08 mm to ±0.15 mm range for small sizes.
Is St52 cold drawn tube seamless?
Yes. DIN 2391 covers cold-drawn seamless precision steel tubes, so a DIN 2391 St52 tube is seamless. A welded version of the same grade is supplied to DIN 2393 (electric-resistance-welded precision tube) and should not be called DIN 2391. Specify seamless or welded explicitly on the order.
What is the St52 yield strength?
The minimum yield strength of St52 is 355 MPa (about 51 ksi) in the normalized or annealed delivery condition. This is the value most specifications and the '52' designation refer to. Cold-worked delivery conditions can push the measured yield higher, but 355 MPa is the design minimum.
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