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March 23, 2026
DIN 2391 Seamless Precision Steel Tubes
DIN 2391 is a German standard for cold-drawn or cold-rolled seamless precision steel tubes, now superseded by EN 10305-1 (Steel tubes for precision applications – Part 1: Seamless cold drawn tubes). These tubes are characterized by tight dimensional tolerances, smooth surface finish, and consistent mechanical properties, making them ideal for high-precision applications in hydraulic/pneumatic systems, automotive components, and mechanical engineering.
Key Applications
Chemical Composition (Typical Grades)
Below are the standard chemical composition limits for common DIN 2391 steel grades (mass fraction, %):
|
Element |
St 35 (1.0308) |
St 45 (1.0503) |
St 52 (1.0832) |
|---|---|---|---|
| C | ≤ 0.17 | ≤ 0.45 | ≤ 0.22 |
| Si | ≤ 0.35 | ≤ 0.35 | ≤ 0.55 |
| Mn | ≤ 0.80 | ≤ 0.80 | ≤ 1.60 |
| P | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| S | ≤ 0.045 | ≤ 0.045 | ≤ 0.045 |
| Cr | ≤ 0.30 | ≤ 0.30 | ≤ 0.30 |
| Ni | ≤ 0.30 | ≤ 0.30 | ≤ 0.30 |
| Cu | ≤ 0.30 | ≤ 0.30 | ≤ 0.30 |
Mechanical Properties (Tensile Strength & Yield Strength)
Mechanical properties vary by grade and delivery condition (heat treatment). Common conditions include:
Tensile Strength & Yield Strength Table
|
Grade |
Delivery Condition |
Tensile Strength (Rm, MPa) |
Yield Strength (ReH, MPa) |
Elongation (A5, %) |
|---|---|---|---|---|
| St 35 | BKS | 340 – 470 | ≥ 235 | ≥ 25 |
| St 35 | GBK/NBK | 315 – 440 | ≥ 235 | ≥ 25 |
| St 45 | BKS | 420 – 560 | ≥ 340 | ≥ 14 |
| St 45 | GBK/NBK | 380 – 520 | ≥ 315 | ≥ 16 |
| St 52 | BKS | 480 – 620 | ≥ 420 | ≥ 10 |
| St 52 | GBK/NBK | 440 – 580 | ≥ 390 | ≥ 12 |
