Identification method of rectangular tube

1. Fake rectangular tubes are easy to fold. Folding is a variety of broken lines formed by the appearance of rectangular 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 surface of fake and inferior rectangular tubes is often pitted. Pitted surface is the defect of irregular uneven surface of steel caused by serious wear of rolling groove. Due to the pursuit of profits by manufacturers of fake and inferior rectangular tubes, grooving and rolling often exceed the standard.

3. The appearance of fake and inferior rectangular tubes is easy to produce scars. There are two reasons: (1) The material of fake and inferior rectangular tubes is uneven, and there are many impurities. (2) The guide equipment of fake and inferior manufacturers is crude and easy to stick steel.

4. Fake and inferior materials are easy to crack on the surface because their billets are adobe with many pores. The adobe is cracked due to the effect of thermal stress during cooling, and cracks appear after rolling.

5. Fake and inferior rectangular tubes are easy to scratch, because the manufacturer of fake and inferior rectangular tubes has rough equipment, which is easy to produce burrs and scratch the steel surface. Deep scratches reduce the strength of steel.

6. The fake rectangular tube has no metallic luster and is light red, or for two reasons, its billet is adobe. 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 steel will naturally fail to meet the standard.

7. The transverse reinforcement of the fake and inferior rectangular tube is thin and low, which often shows the phenomenon of being insufficient. The reason is that the manufacturer presses the first few times of the waste products due to the large negative tolerance.

8. The cross section of the fake and inferior rectangular tube is oval, because the manufacturer, in order to save data, 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 conform to the specifications for the overall dimensions of the rebar.

9. The composition of good steel is average, 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 materials, that is, uneven and without metallic luster. Moreover, because the manufacturer's products have less head cutting, the head and tail will appear big ears.

10. The material of fake and inferior rectangular tube contains many impurities, the density of steel is too small, and the size is out of tolerance. If there is no vernier caliper, it can be stopped weighing and checking. For example, for rebar 20, the rule negative tolerance in the specification is 5%. When the size is 9M, the theoretical weight of a single rebar is 120kg. Its weight should be 120 X (l-5%)=114kg. If the theoretical weight of a single rebar measured is smaller than 114kg, it is% of fake and inferior steel. Generally speaking, the whole phase weighing effect will be very good, mainly considering the cumulative error and probability theory.

11. The reason why the inner diameter of fake and inferior rectangular tubes fluctuates greatly is that:; a. The steel temperature is unstable and there are male and female surfaces. b. The composition of steel is uneven. c. 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 Haoguan are comparable to the standard.

13. The spacing of rectangular pipes with a diameter of more than 16 is more than IM.

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

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