DIN2391 St35 NBK is the standard applicable to Seamless precision steel tubes
DIN 2391 seamless precision tubes applications —Used in Hydraulic & pneumatic cylinder, Mechanical and Automotive engineering
Technical delivery conditions:
- Part 1: Seamless cold drawn tubes.
Chemical Composition
| Standard | Grade | Chemical Components (%) | |||||
| Symbol | Material No. | C | Si | Mn | P | S | |
| DIN2391 | St 35 | 1.0308 | ≤0.17 | ≤0.35 | ≥0.40 | ≤0.025 | ≤0.025 |
Click to download the details of DIN2391 ST35 NBK seamless tubes.
Delivery Conditions
The tubes shall be manufactured from cold drawn or cold rolled processes. The tubes shall be supplied in one of the delivery conditions as follows:
| Designation | Symbol | Description |
| Cold finished (hard) | BK | Tubes do not undergo heat treatment following the final cold forming and thus, have a rather high resistance to deformation. |
| Cold finished (soft) | BKW | The final heat treatment is followed by cold drawing involving limited deformation. Appropriate further processing allows a certain degree of cold forming (e.g. bending, expanding). |
| Cold finished and stress-relieved | BKS | Heat treatment is applied following the last cold forming process. Subject to appropriate processing conditions, the increase in the residual stresses involved enables both forming and machining to a certain degree. |
| Annealed | GBK | The last cold forming process is followed by annealing in a controlled atmosphere. |
| Normalized | NBK | The last cold forming process is followed by annealing above the upper transformation point in a controlled atmosphere. |
Mechanical Properties
| Mechanical properties at room temperature | |||||||||||||
| Steel Grade | Minimum values for the delivery condition | ||||||||||||
| Steel Name | Steel Number | BK | BKW | BKS | GBK | NBK | |||||||
| Rm | A % | Rm | A % | Rm | ReH | A % | Rm | A % | Rm | ReH | A % | ||
| Mpa | Mpa | Mpa | Mpa | Mpa | Mpa | Mpa | |||||||
| St 35 | 1.0308 | 480 | 6 | 420 | 10 | 420 | 315 | 14 | 315 | 25 | 340 to 470 | 235 | 25 |
Inspection and test list for the DIN 2391 Standard
| Inspection or test types | Test frequency | |
| Internal test | Acceptance test | |
| Chemical analysis | M | M |
| Tensile testing | M | One per tested batch |
| Flattening test or extension test | M | Two per tested batch |
| Dimension verification | M | M |
| Visual inspection | M | M |
| NDT in order to identify leaks | Individual | Individual |
Standard: DIN 2391
Description Name: DIN 2391 Seamless cold drawn tubes, DIN 2391 Seamless precision steel tubes, ST35 Precision tubes, ST45 Precision tubes, ST52 Precision tubes, Seamless precision tubes, DIN 2391 ST35 Seamless precision steel tubes, DIN 2391 ST45 Seamless precision steel tubes, DIN 2391 ST52 Seamless precision steel tubes, ST 52 Honed tubes, ST52 cylinder tubes
Size:
OD.: 4mm-89mm
W.T.: 0.6mm-20mm
Shape: Round
Production type: Cold drawn or cold rolled
Length: Single random length/ Double random length or as customer’s actual request max length is 10m
Grade: St35
Note:
- Mill test certificates will be issued according to EN10204.3
- The tubes Shall be Seamless cold drawn or cold rolled.
- The manufacture should have TS16949 certificate or ISO9000 certificate.
Protection and Packing:
- Packed in wooden box or bundles protected with plastic paper, and suitably protected for sea-worthily delivery or as requested.
- The tubes shall be delivered with a temporary corrosion protection. The type of protection shall be at the discretion of the manufacturer
Application:
apply to the Precision steel tubes used.
Photos for DIN2391 ST35 NBK
DIN2391 ST35 NBK seamless tubes
DIN2391 ST35 NBK surface
DIN2391 ST35 NBK OD inspection
DIN2391 ST35 NBK thickness inspection
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