What Is EN 10305-4?
EN 10305-4 is the European standard for seamless cold drawn precision steel tubes for mechanical and general engineering purposes. Precision tubes are manufactured with tightly controlled outside diameter and wall thickness tolerances, a smooth surface, and consistent straightness, so they can be used directly in machined components and hydraulic and pneumatic systems with minimal additional processing. The standard covers the steel grades E215, E235 and E355.
Steel Grades Covered
The standard defines three grades with steel numbers as follows: E215 (1.0212), E235 (1.0308) and E355 (1.0580). E235 is the most widely used grade, combining good strength with excellent cold formability and weldability. The letter E indicates a precision tube application and the number refers to the minimum yield strength in MPa.
Chemical Composition
Composition limits of the grades are given below. Elements not listed must not be added intentionally without the agreement of the purchaser, except for elements added for deoxidation and nitrogen-binding purposes. Steelmaking must avoid the introduction of unwanted elements from scrap or other materials.
| Steel grade | C max | Si max | Mn max | P max | S max | Al total min |
|---|---|---|---|---|---|---|
| E215 (1.0212) | 0.10 | 0.05 | 0.70 | 0.025 | 0.025 | 0.025 |
| E235 (1.0308) | 0.17 | 0.35 | 1.20 | 0.025 | 0.025 | 0.015 |
| E355 (1.0580) | 0.22 | 0.55 | 1.60 | 0.025 | 0.025 | 0.020 |
Mechanical Properties
The mechanical properties of the three grades are summarized below. Values are guaranteed on the final tube. The grades have an intrinsic minimum transverse impact energy of 27 J at 0 °C.
| Steel grade | Yield strength ReH min (MPa) | Tensile strength Rm (MPa) | Elongation A min (%) |
|---|---|---|---|
| E215 (1.0212) | 215 | 290 - 430 | 30 |
| E235 (1.0308) | 235 | 340 - 480 | 25 |
| E355 (1.0580) | 355 | 490 - 630 | 22 |
For tubes with outside diameter up to 30 mm and wall thickness up to 3 mm, the minimum yield strength values are 10 MPa lower than the values in the table.
Dimensional Accuracy and Delivery Condition
Precision cold drawn tubes are supplied in the cold drawn condition or after light annealing, depending on the required properties and surface finish. Dimensional tolerances are much tighter than for standard hot-finished tubes, which is why the tubes can be used directly for cylinder barrels, shafts and bushings. Confirm the tolerance class, surface condition and straightness with the mill.
Applications
Typical applications of EN 10305-4 E235 tubes include hydraulic and pneumatic cylinder barrels, shock absorbers, machine tool components, rollers, shafts, bushings, and precision mechanical parts in automotive and general engineering.
FAQ About EN 10305-4 E235 Tubes
What does E235 mean?
E identifies a precision tube application and 235 is the minimum yield strength of the grade in MPa.
What is steel number 1.0308?
1.0308 is the numeric designation of E235 in the European steel numbering system EN 10027-2.
Is EN 10305-4 tube seamless?
Yes. Part 4 of EN 10305 covers seamless cold drawn tubes; other parts of the standard cover welded precision tubes.
What impact energy is guaranteed?
The grades have an intrinsic minimum transverse impact energy of 27 J at 0 °C.
Can E235 tubes be welded?
Yes. E235 has low carbon and good weldability; it is frequently welded in hydraulic and mechanical assemblies with standard procedures.
What surface finish do precision tubes have?
Cold drawn precision tubes have a smooth, scale-free surface, typically with roughness values low enough for direct use in sealing applications.