Carbon Steel Rectangular Tubing

1. Fake and inferior rectangular pipe is easy to fold. Folding is a variety of broken lines formed on the surface of a rectangular tube. This defect often runs through the longitudinal length of the product. The reason for the folding is that because of the pursuit of high efficiency of fake and inferior manufacturers, the amount of pressure is large, the ear is produced, the next rolling is folded, the folded product will crack after bending, and the strength of steel is greatly reduced.

2. The appearance of fake rectangular pipe often have pockmarked phenomenon. Pockmarks are irregular and uneven defects on the steel surface caused by serious wear of rolling groove. Groove rolling often exceeds the standard due to the pursuit of profit of shoddy rectangular pipe manufacturers.

3. The surface of fake and inferior rectangular tube is easy to produce scarring. There are two reasons :(1). Fake rectangular tube material is not uniform, impurities. (2). Shoddy manufacturers guide equipment simple, easy to stick to steel, these impurities

4. Shoddy material surface easy to crack, the reason is that its billet is adobe, adobe pores, adobe in the cooling process due to the role of thermal stress, crack, after rolling there are cracks.

5. Shoddy rectangular pipe is easy to scratch, the reason is that the shoddy rectangular pipe manufacturer equipment is simple, easy to produce burr, scratch the steel surface. Deep scratches reduce the strength of the steel.

6. Fake rectangular tube without metallic luster, light red or reasons for two points, its billet is adobe.The rolling temperature of shoddy materials is not standard, their steel temperature is measured visually, so it can not be rolled in accordance with the specified austenite area, and the performance of steel naturally cannot reach the standard.

7. The transverse bars of fake and inferior rectangular tubes are thin and low, which often appear to be filled with dissatisfaction. The reason is that the manufacturer has a large negative tolerance and the pressure of the first few lines of the finished products

8. The cross section of the fake rectangular tube is oval, the reason is that the manufacturer in order to save materials, the pressure of the finished roller in front of the two is large, the strength of this rebar is greatly reduced, but also does not meet the standard of the shape size of rebar.

9. The composition of high-quality steel is uniform, the tonnage of the cold shearing machine is high, and the end face of the cutting head is smooth and tidy. Because of the poor material of the fake and inferior materials, the end face of the cutting head often has the phenomenon of falling flesh, that is, the uneven and non-metallic luster. And because the manufacturer product cuts the head less, the head and tail can appear big ear.

10. Fake rectangular tube material contains many impurities, the density of steel is small, and the size is out of tolerance in the case of no vernier caliper, it can be weighed and checked. For example, for rebar 20, the national standard stipulates that the maximum negative tolerance is 5%. When measuring 9M, its theoretical weight of a single root is 120kg, and its minimum weight should be: 120x (L-5%) = 114kg. The actual weight of a single root measured is smaller than 114kg, so it is fake steel %. In general, integer quantities work better, mainly because of cumulative errors and probability theory.

11. The inner diameter of shoddy rectangular pipe fluctuates greatly, for the following reasons: Steel temperature instability has Yin - Yang surface. The composition of steel is uneven. Because the equipment is simple, the foundation strength is low, the mill's bounce is big. There will be a larger change within the same week, so that the reinforcement is not uniform and easy to fracture.

12. The trademark and printing of quality tubes are quite standard.

13. The spacing of rectangular tubes with diameters above 16 is above IM.

The longitudinal bars of shoddy steel rebar are often wavy.