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How to identify the quality of steel pipe
Time:
2024-01-12
Fifteen. Shoddy steel pipe manufacturers because there is no driving, so the packaging is loose. The sides are oval.
1. Shoddy steel pipes are prone to folding.
Folding is a variety of broken lines formed on the surface of the steel pipe, and this defect often runs through the longitudinal side of the entire product. The reason for folding is because the shoddy manufacturers pursue high efficiency, the amount of pressure is too large, the ear is produced, the next rolling will fold, the folded product will crack after bending, and the strength of the steel will decrease.
2. The appearance of shoddy steel pipes is often pockmarked.
Pitted surface is the irregular uneven defect of steel surface caused by severe groove wear. Because shoddy steel pipe manufacturers want to pursue profits, there are often excessive groove rolling.
3. The surface of shoddy steel pipes is prone to scarring.
There are two reasons: (1). The material of shoddy steel pipe is not uniform, and there are many impurities. (2). Shoddy material manufacturers guide equipment is simple, easy to stick steel, these impurities bite the roll is easy to produce scars.
4. The surface of shoddy materials is prone to cracks, the reason is that its billet is adobe, adobe porosity, adobe in the cooling too
Due to the action of thermal stress in the process, cracks occur, and cracks occur after rolling.
5. Shoddy steel pipes are easy to scratch, the reason is that shoddy steel pipe manufacturers have simple equipment, easy to produce burrs, scratch the steel surface. Deep scratching reduces the strength of steel.
6. The fake steel pipe has no metallic luster and is light red or similar to the color of pig iron, for two reasons. 2, the rolling temperature of shoddy materials is not standard, their steel temperature is visually measured, so that it can not be rolled according to the prescribed austenitic area, the performance of steel naturally can not meet the standard.
Seven. The transverse bar of shoddy steel pipe is thin and low, and the phenomenon of filling is often dissatisfied, because the manufacturer in order to achieve a large negative tolerance, the pressure of the first few passes of the finished product is too large, the iron shape is too small, and the pass shape is not satisfied.
8. The cross section of the shoddy steel pipe is elliptical, because the manufacturer in order to save materials, the pressure of the first two rolls of the finished product is too large, the strength of this rebar is greatly reduced, and it does not meet the standard of the external size of the rebar.
9. The composition of high-quality steel is uniform, the tonnage of the cold shear machine is high, the end face of the cutting head is smooth and neat, and the shoddy material is poor, the end face of the cutting head often has the phenomenon of falling meat, that is, uneven, and no metallic luster. And because the shoddy material manufacturers products cut less head, head and tail will appear big ears.
10. The fake steel pipe material contains more impurities, the density of the steel is small, and the size is serious, so it can be weighed and checked without a vernier caliper. For example, for rebar 20, the maximum negative tolerance stipulated in the national standard is 5%, the theoretical weight of its single root is 120 kg when the height is 9M, its minimum weight should be: 120 X (l-5%) =114 kg, weighing out the actual weight of a single root is smaller than 114 kg, it is shoal steel, because its negative tolerance exceeds 5%. In general, it is better to integrate proportional quantities, mainly considering the problem of cumulative error and probability theory.
11. The inner diameter of shoddy steel pipe fluctuates greatly, the reason is; l, steel temperature instability has Yin and Yang. 2, the composition of steel is not uniform. 3, due to the simple equipment, low foundation strength, the mill bounce. There will be a large change in the same week, such reinforcing steel uneven force is easy to fracture.
12. The quality of the logo and printing are relatively standardized.
13. Three steel pipe diameter of more than 16 large threads, the spacing between the two trademarks are above IM.
14. The longitudinal bar of shoddy steel rebar is often wavy.
Fifteen. Shoddy steel pipe manufacturers because there is no driving, so the packaging is loose. The sides are oval.
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