There are 15 identification methods for fake and inferior square tubes

1. Fake and inferior square tubes are easy to fold.  

Folding is a variety of broken lines formed on the surface of square tubes, and this defect often runs through the longitudinal direction of the whole product. The reason for folding is that the fake and inferior manufacturers pursue efficiency, and the reduction is too large to produce ears. The folding will occur during the next rolling. The folded products will crack after bending, and the strength of steel will drop greatly.  

2. The appearance of fake and inferior square tubes is often pitted.  

Pitted surface is the irregular uneven defect on the steel surface caused by the serious wear of rolling groove. Because of hypocrisy Square tube manufacturer In pursuit of profit, it often appears that groove rolling exceeds the standard.  

3. The surface of fake and inferior square tubes is easy to produce scars.  

There are two reasons: (1). The fake and inferior square tubes are made of uneven materials with many impurities. (2)。 The guide equipment of fake and inferior material manufacturers is rough and easy to stick steel, and these impurities are easy to produce scars after biting the rolls.  

4. The surface of fake and inferior materials is easy to crack, because its billet is adobe, which has many pores and is too cooled

Cracks are produced due to thermal stress during the rolling process, and cracks will appear after rolling.  

5. Fake and inferior thick wall pipes are easy to scratch, because the equipment of the manufacturer of fake and inferior square pipes is rough, which is easy to produce burrs and scratch the steel surface. Deep scratches reduce the strength of steel.  

6. Fake thick wall Seamless square tube There is no metallic luster, and it is light red or similar to pig iron because its billet is adobe. 2. The rolling temperature of fake and substandard materials is not standard, and their steel temperature is visually inspected, so the rolling cannot be stopped according to the regular austenite area, and the performance of the steel will naturally fail to meet the standard.  

7. The transverse reinforcement of the fake and inferior square tube is thin and low, which often shows the phenomenon of insufficient filling. The reason is that the manufacturer, in order to reach a large negative tolerance, has too much pressing down in the first few passes of waste products, too small iron mold, and insufficient hole mold.  

8. The cross section of the fake and inferior square tube is oval. The reason is that the manufacturer, in order to save materials, has a large reduction in the first two passes of the waste roll, which greatly reduces the strength of this kind of rebar, and does not meet the standards for the overall dimensions of the rebar.  

9. The composition of good steel is uniform, the tonnage of the cold shear is high, and the end face of the cutting head is smooth and uniform, while the end face of the cutting head of fake and inferior materials often has flesh loss due to poor material quality, that is, uneven and without metallic luster. Moreover, because the products of fake and inferior materials manufacturers are cut less, the head and tail will appear big ears.  

10. The material of fake and inferior square tube contains many impurities, the density of steel is too small, and the size is out of tolerance seriously. Therefore, if there is no vernier caliper, you can stop weighing and checking it. For example, for deformed steel bar 20, the large negative tolerance specified in the national standard is 5%. When sizing 9M, its single theoretical weight is 120 kg, and its small weight should be 120 X (l-5%)=114 kg. If the single theoretical weight measured is smaller than 114 kg, it is fake and inferior steel, because its negative tolerance exceeds 5%. Generally speaking, the whole phase weighing effect will be much better, mainly considering the cumulative error and probability theory.  

11. The inner diameter of the fake and inferior square tube fluctuates greatly for the following reasons:; l. The steel temperature is unstable and there are male and female surfaces. 2. The composition of steel is uneven. 3. Due to rough equipment, low foundation strength and large bounce of rolling mill. There will be large changes in the same week, so the uneven stress of the reinforcement is prone to fracture.  

12. The trademark and printing of a good tube are quite standard.  

13. For the large thread with a diameter of more than 16 of the square tube, the distance between the two trademarks shall be more than IM.  

14. The longitudinal reinforcement of deformed steel bars made of fake and inferior steel is often wavy.  

15. The manufacturer of fake and inferior square tubes did not drive the train, so the packing was lax. The side is oval.

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