China DIN2391 C St35 St37.4 Cold Drawn Steel Tube Nbk Condition

1.Descriptions

NameDIN2391/C St35/St37.4 Cold Drawn Steel Tube NBK ConditionSpecificationDIN2391-94/C, EN10305-1, EN10305-4, SAE J524, GB/T3639-2009Steel GradeSt35, St37.4, St45, St52.4, E235, E255, E355SizeOD:3-76mm, wall thickness: 0.5-6mmLength4m,6m or customizedDelivery ConditionsNBK(+N), BK(+C), GBK(+A), BKW(+LC), BKS(+SR)Featureshigh cleanness inside wall, No deformation after cold bending, no crack after flaring and flattening, complicated geometrical forming and machining can be realizedApplicationsUsed in hydraulic system, automobile and in the occasion where the high precision, brightness, cleanness and mechanical properties of the tube are requiredPackingPlastic film & Knitting Bundled, Plywood Case or as requestDelivery Time20-30days after order /confirm/ied

2. Chemical Composition (cast analysis

Steel Gr.Steel No.Chemical Compositions(%by mass)C(max)Si(max)MnP(max)S(max)Al(min)TotalSt35, St37.4(E235)1.03050.170.35≥0.400.0250.0250.015St45(E255)1.04080.210.35≥0.400.0250.0250.015St52, St52.4(E355)1.05080.220.55≤1.600.0250.0250.020

3. Mechanical Properties (at room temperature)

Steel Gr.Steel
No.BKBKWBKSGBKNBKRm
MPaA
%Rm
MPaA
%Rm
MPaReH
MPaA
%Rm
MPaA
%Rm
MPaReH
MPaA
%MinMinMinMinMinMinMinMinMin MinMinSt35(E235)1.03054806420104203151431525340-47023525St45(E255)1.0408580552085203751239021440-57025521St52(E355)1.0508640458075804201049022490-63035522

4. Production Flow Chart
Key Procedures Descriptions:
Cold Rolling
Tube rolling uses compression to reduce the size of seamless tubes. It utilizes one or two sets of rolls with constant
cross-section grooves on the circumference of the tube. The rolls are driven by rack and pinion gears of different
radii along profiled cams, completing multiple 360º rotations around the tube
Tube rolling is a very precise method of reducing very thin walled and/or smaller diameter tubes, and is often used
as the final cold working step. By rolling, we're able to achieve exceptional control over dimensional tolerances
and surface finish while also minimizing material loss and improving the metal's microstructure.
Cold Drawing
Cold drawing reduces the diameter by pulling the tube through a die that is smaller than the tube. In order to fit the tube
into the die, one end is swaged thereby reducing the diameter of the leading end before drawing. Next, the narrowed
end is passed through the die and clamped to a drawing trolley which pulls the tube through the die.
Annealing
Annealing is used to soften the metal before further cold working or fabrication processes, and improves the overall
metallurgical microstructure of the tube. During tube reduction or cold drawing, it can become hard and somewhat brittle.
To be able to draw the tube again, stresses formed during cold working need to be removed to return the material to its
normal state.
During annealing the tube is heated to a controlled temperature and soak time. Through this process the tube remains in
shape, but the grains in the structure of the tube reform into a regular unstressed pattern. The resulting annealed tube is
softer and suitable for redrawing
Straightening
Drawing and annealing generally results in some degree of bowing, producing a slight bend in the tubing. In order to
make the tubes straight, we use multiple roll mechanical straighteners to implement this procedure, Straightening can
introduce slight changes to the size and mechanical properties of the tubing, so these aspects are very carefully
controlled during the process.
5. Inspection and Tests
We inspect all lots of tubing before shipment to ensure that every aspect of the customer's order has been met.
Our in-house inspection and tests capabilities include:Chemical Composition TestVisual inspectionDimensional inspectionSurface roughness testingEddy Current testingHydrostatic pressure testingDestructive mechanical testing:- Yield Strength
- Tensile Strength
- Elongation
- Hardness testing
- bending, flattening, and flaring
All shipments include a full Test Certificate showing all required test results and verifying compliance with the order requirements.
6. Packing and Shipments
7. Applications