What is Cold Drawn Welded Tube E355 According to DIN EN 10305-2

Cold drawn welded tube E355 is a precision welded steel tube manufactured according to DIN EN 10305-2 standard. The tubes are produced using high frequency welding (HFW) followed by cold drawing processes to improve dimensional accuracy, surface finish, and mechanical properties.

Key features of cold drawn welded tube E355:

High dimensional accuracy (tight OD/ID tolerances)

Excellent surface finish (suitable for honing)

High mechanical strength (yield strength ≥355 MPa)

Uniform wall thickness (reduces material waste)

Reliable weld seam quality (ultrasonically tested)

Multiple delivery conditions (+C, +LC, +SR, +A, +N)

These properties make cold drawn welded tube E355 ideal for telescopic cylinders, hydraulic cylinder barrels, mechanical structures, and engineering applications requiring higher strength than E235.

DIN EN 10305-2 standard covers precision cold drawn welded steel tubes for mechanical and hydraulic purposes. The E355 material grade indicates minimum yield strength of 355 MPa with various heat treatment conditions available after cold drawing.

DIN EN 10305-2 Standard Overview for E355 Tubes

DIN EN 10305-2 specifies technical delivery conditions for cold drawn welded precision tubes used in mechanical and hydraulic applications.

Key requirements of DIN EN 10305-2 for E355 tubes include:

Chemical composition limits (C, Si, Mn, P, S)

Mechanical property requirements (yield strength, tensile strength, elongation)

Dimensional tolerances (OD, ID, wall thickness, straightness, ovality)

Surface condition requirements (roughness, defects)

Heat treatment conditions (+C, +LC, +SR, +A, +N)

Testing and inspection procedures (ultrasonic, eddy current, tensile, hardness)

Cold drawn welded tube E355 under DIN EN 10305-2 ensures high performance and reliable service life in demanding hydraulic cylinder applications where higher strength than E235 is required.

Chemical Composition of Cold Drawn Welded Tube E355

The chemical composition of cold drawn welded tube E355 ensures high strength, good weldability, and consistent hardenability for hydraulic cylinder manufacturing.

Chemical Composition of E355 According to DIN EN 10305-2

Element	Composition (%)
Carbon (C)	≤ 0.22
Silicon (Si)	≤ 0.55
Manganese (Mn)	≤ 1.60
Phosphorus (P)	≤ 0.025
Sulfur (S)	≤ 0.025

The controlled chemical composition allows cold drawn welded tube E355 to achieve excellent mechanical strength, low carbon equivalent (CEV) , and stable performance in telescopic cylinder manufacturing and high-pressure hydraulic systems.

Mechanical Properties of Cold Drawn Welded Tube E355

Cold drawn welded tube E355 offers high strength and reliable mechanical performance under cyclic hydraulic pressure. The mechanical properties vary depending on the delivery condition.

Mechanical Properties of E355 According to DIN EN 10305-2

Delivery Condition	Yield Strength ReH Min. (MPa)	Tensile Strength Rm (MPa)	Elongation A Min. (%)
+C (Cold drawn/hard)	≥ 355	640 – 880	≥ 4
+LC (Cold drawn/soft)	≥ 355	590 – 780	≥ 6
+SR (Stress relieved)	≥ 355	590 – 740	≥ 10
+A (Annealed)	≥ 355	490 – 690	≥ 22
+N (Normalized)	≥ 355	490 – 690	≥ 22

These mechanical properties make cold drawn welded tube E355 suitable for telescopic cylinders, hydraulic cylinder tubes, heavy equipment structures, and mobile hydraulics requiring higher strength than E235.

Delivery Conditions for Cold Drawn Welded Tube E355 (EN 10305-2)

Cold drawn welded tube E355 can be supplied in five different delivery conditions according to DIN EN 10305-2. Each condition offers specific mechanical properties and internal stress states for different applications.

+C – Cold Drawn / Hard (BK equivalent)

+C indicates no heat treatment after the final cold drawing process.

Characteristics: High strength, low elongation, significant residual stress

Applications: As-drawn condition for further cold forming or machining

Hardness: Highest among all conditions

+LC – Cold Drawn / Soft (BKW equivalent)

+LC indicates a light drawing pass after final heat treatment.

Characteristics: Balanced strength and ductility

Applications: Suitable for moderate bending and forming operations

Elongation: Higher than +C, lower than +SR

+SR – Cold Drawn and Stress Relieved (BKS equivalent)

+SR indicates stress relief heat treatment in a controlled atmosphere after cold drawing.

Characteristics: Reduced internal residual stress, improved dimensional stability

Applications: Preferred for hydraulic cylinder barrels and telescopic cylinders

Advantages: Minimizes distortion during machining, maintains high strength

+A – Annealed (GBK equivalent)

+A indicates annealing in a controlled atmosphere after cold drawing.

Characteristics: Softest condition, lowest strength, highest ductility

Applications: Suitable for severe cold forming operations

Elongation: Highest among all conditions (≥22%)

+N – Normalized (NBK equivalent)

+N indicates normalizing in a controlled atmosphere after cold drawing.

Characteristics: Uniform grain structure, consistent mechanical properties

Applications: Suitable for welding and subsequent heat treatment

Advantages: Best combination of strength and toughness

 

Comparison of Delivery Condition Symbols: EN 10305 vs DIN 2391

EN 10305 Symbol	DIN 2391 Symbol
+C	BK
+LC	BKW
+SR	BKS
+A	GBK
+N	NBK

For telescopic hydraulic cylinder applications, Womic Steel recommends E355+SR as the most popular choice due to its stress relieved condition, excellent dimensional stability, and high yield strength.

Inner Surface Honing for Cold Drawn Welded Tube E355

To meet the demanding requirements of hydraulic cylinder applications, cold drawn welded tube E355 can be supplied with precision inner surface finishing services.

What is Inner Surface Honing?

Inner surface honing is a precision machining process that improves the internal surface finish and dimensional accuracy of hydraulic cylinder tubes. The process uses abrasive stones to remove microscopic irregularities and achieve a cross-hatch pattern that retains lubricating oil.

Honing vs. Skiving and Roller Burnishing (SRB)

Process	Description	Surface Finish (Ra)	Advantages
Honing	Abrasive stones remove material to improve roundness and finish	0.2 – 0.4 μm	Corrects ovality, improves straightness, creates oil-retaining pattern
Skiving & Roller Burnishing (SRB)	Cutting tool removes surface layer, then rollers smooth the surface	0.1 – 0.3 μm	Faster process, work-hardened surface, excellent finish

Benefits of Inner Surface Honing for E355 Tubes

Reduced friction between piston seals and cylinder bore

Improved seal life (less wear on seals)

Higher pressure capacity (smoother surface reduces stress concentrations)

Better corrosion resistance (smoother surface resists pitting)

Enhanced oil film retention (cross-hatch pattern)

Womic Steel Inner Surface Honing Capability for E355 Tubes

Inner diameter range: 30mm – 330mm (after honing)

Surface finish: Ra ≤ 0.4 μm (standard), Ra ≤ 0.2 μm (upon request)

Straightness: Improved after honing process

Tolerance: H8, H9, H10 or as specified by customer

Cold drawn welded tube E355 with honed inner surface is the preferred choice for telescopic cylinders, heavy-duty hydraulic cylinders, and precision mechanical applications requiring smooth piston movement and leak-free operation.