Cold drawn or cold-rolled precision seamless steel tubes
Relative standard :
GB/T222 permissible tolerance for chemical composition of steel products.
GB/T223.5 Steel and iron-Determination of acid-soluble silicon and total silicon content-Reduced molybdosilicate spectro photometric method(GB/T223.5-2008,ISO 4829-1:1986,ISO 4829-2:1988,MOD)
Mechanical properties
Steel grade 10# 20# 35# 45# Q345B
| Steel grade | deliver conditions |
| +C | +LC | +SR | +A | +N |
| Rm/Mpa | A/% | Rm/Mpa | A/% | Rm/Mpa | ReH/Mpa | A/% | Rm/Mpa | A/% | Rm/Mpa | ReH/Mpa | A/% |
| No less than |
| 10 | 430 | 8 | 380 | 10 | 400 | 300 | 16 | 335 | 24 | 320-450 | 215 | 27 |
| 20 | 550 | 5 | 520 | 8 | 520 | 375 | 12 | 390 | 21 | 440-570 | 255 | 21 |
| 35 | 590 | 5 | 550 | 7 | | | | 510 | 17 | ≥460 | 280 | 21 |
| 45 | 645 | 4 | 630 | 6 | | | | 590 | 14 | ≥540 | 340 | 18 |
| Q345B | 640 | 4 | 580 | 7 | 580 | 450 | 10 | 450 | 22 | 490-630 | 355 | 22 |
Deliver condition:
Cold working/Hard condition:+C
No heat treatment after the final cold working process.
Cold working/Soft condition:+LC
After the final treatment there is a suitable cold working process
Stress relieving annealed conditio:+SR
After the final cold working process there is a stress relief heat treatment in a controlled atmosphere
Annealed condition:+A
After the final cold working process the tubes are fully annealed in a controlled atomosphere.
Normalised condition:+N
After the final cold working operation the tubes are normalized in a controlled atomosphere.
The permissible tolerances of the internal and external diameter unit:mm
| Wall thickness(S)/extrernal diameter | Permissible tolerance |
| S/D≥1/20 | According to the specified value of the table 1 |
| 1/40≤S/D＜1/80 | According to 1.5 times of specified value of the table 1 |
| S/D＜1/40 | According to double of specified value of the table 1 |
Length is 2000-12000mm Fixed length and multiple length is available.
Tolerance for length , a)the length ≤5000mm +5,0mm
B)the length ＞5000mm +10,0mm
Every multiple length should leave incision margin according to the following requirement for the steel tubes delivered by multiple length.
- External diameter≤159mm:5mm~10mm
- External diameter＞159mm:10mm~15mm
Curvature:≤3.0mm/m
The steel tubes’ total length curvature external diameter ≥16mm
- ReH≤500Mpa,≤0.15%L
- ReH＞500Mpa,≤0.20%L
QUALITY CONTROL
1~ Incoming Raw Material Inspection
2~ Raw Material Segregation to avoid steel grade mix-up
3~ Heating and Hammering End for Cold Drawing
4~ Cold Drawing and Cold Rolling, on line inspection
5~ Heat Treatment, +A, +SRA, +LC, +N, Q+T
6~ Straightening-Cutting to specified length-Finished Measuring Inspection
7~ Machanical Testing in own labs with Tensile Strength, Yield Strength, Elongation, Hardness, Impact, Mictrostruture etc
8~ Packing and Stocking.
100% of our steel tubes are dimensionally checked
100% of our steel tubes are visually checked to assure they have a perfect surface condition and no surface defects.
100% eddy current test and ultrosonic test to eliminate longitudinal and transversal defects.
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350mm Cold Drawn Carbon Seamless Steel Pipe For Chemical Composition Images
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