Bright annealed / NBK Precision Seamless Steel Tube according to DIN 2391 / EN 10305-1 / EN10305-4
Main Features:
High accuracy, excellent brightness, free of rust, no oxide layer, no cracks and other defects, high inside wall cleanness. And the high-pressure carbon steel tubes are able to stand high pressure, No deformation after cold bending, no cracking after flaring and flattening. The complicated geometrical forming and machining can be realized.
▪ Main Application:
Precision tubes for hydraulic systems, automobiles, Diesel Engines, machinery, and other areas which require high precision, cleanness, and high mechanical properties performance.
▪ Standard:
DIN 2391, EN 10305-1, EN 10305-4
▪ Materials:
ST35, ST37.4, ST37, ST45, ST52, ST52.4, E235, E255, E355.
▪ Delivery condition:
NBK, bright anaerobic normalizing.
EN 10305-1 Chemical composition(%)
| Steel grade
Name | Steel
Number | C(% max) | Si(% max) | Mn(% max) | P(% max) | S(% max) |
| E215 | 1.0212 | 0.10 | 0.05 | 0.70 | 0.025 | 0.015 |
| E235 | 1.0308 | 0.17 | 0.35 | 1.20 | 0.025 | 0.015 |
| E355 | 1.0580 | 0.22 | 0.55 | 1.60 | 0.025 | 0.015 |
EN 10305-1 Mechanical and technological properties
Yield strength
(min Mpa) | Tensile strength
(min Mpa) | Elongation
(min %) |
| 215 | 290-430 | 30 |
| 235 | 340-480 | 25 |
| 355 | 490-630 | 22 |
Condition on delivery of EN 10305-1:
| Term | Symbol | Explanation |
| Cold-finished/hard
(cold-finished as-drawn) | BK | No heat treatment after the last cold-forming process. The tubes, therefore, have only low deformability. |
| Cold-finished/soft
(lightly cold-worked) | BKW | After the last heat treatment, there is a light finishing pass (cold drawing) With proper subsequent processing, the tube can be cold-formed (e.g. bent, expanded) within certain limits. |
| Annealed | GBK | After the final cold-forming process the tubes are annealed in a controlled atmosphere or under vacuum. |
| Normalized | NBK | The tubes are annealed above the upper transformation point in a controlled atmosphere or under a vacuum. |
Product Tags:
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Bright Annealed NBK Seamless Precision Steel Tube DIN 2391 EN 10305-1 Images
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