How to Identify Fake and Inferior Rectangular Tubes?

Identification method of fake and inferior rectangular tube

1) Fake and inferior materials are prone to cracks on the surface. The reason is that its blank is adobe, and the adobe has many pores. During the cooling process, the adobe is subjected to thermal stress, resulting in cracks. After rolling, there are cracks.

2) The fake and inferior rectangular tube has no metallic luster and is light red or there are two reasons. Its blank is adobe. The rolling temperature of fake and inferior materials is not standard, and their steel temperature is measured visually, so that it cannot be rolled according to the specified austenite area, and the performance of the steel will naturally fail to meet the standard.

3) Fake and inferior rectangular tubes are prone to folding. Folds are various fold lines formed on the surface of the rectangular tube, and this defect often runs through the longitudinal direction of the entire product. The reason for the folding is that the counterfeit and inferior manufacturers pursue high efficiency, and the reduction amount is too large, resulting in ears, and folding occurs during the next rolling. The folded product will crack after bending, and the strength of the steel will be greatly reduced.

4) The cross-section of the fake and inferior rectangular pipe is oval. The reason is that in order to save materials, the reduction amount of the first two passes of the finished roll is too large. standard.

5) The appearance of the fake and inferior rectangular tube often has a pockmarked surface. The pitted surface is the irregular unevenness on the surface of the steel due to the serious wear of the rolling groove. Because the manufacturers of fake and inferior rectangular pipes want to pursue profits, it often occurs that the groove rolling exceeds the standard.

6) The composition of high-quality steel is uniform, the tonnage of the cold shearing machine is high, and the end surface of the cutting head is smooth and tidy. However, due to the poor material of the fake and inferior material, the end surface of the cutting head often has the phenomenon of meat loss, that is, unevenness and no metallic luster. And because the manufacturer's products have less head cut, big ears will appear on the head and tail.

7) The surface of the fake and inferior rectangular tube is prone to scarring. There are two reasons:

a. The material of the fake and inferior rectangular tube is uneven and there are many impurities.

b. The guide equipment of fake and inferior manufacturers is simple and easy to stick to steel. These impurities

8) The transverse ribs of the fake and inferior rectangular tubes are thin and low, and the phenomenon of filling is often not satisfied.

9) The material of the fake and inferior rectangular tube contains a lot of impurities, the density of the steel is too 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 the fixed length is 9M, its single theoretical weight is 120 kg, and its minimum weight should be: 120 X (l-5%) = 114 kg , the actual weight of a single piece is less than 114 kg, it is fake and inferior steel. Generally speaking, the effect of whole phase weighing will be better, mainly considering the problem of cumulative error and probability theory.

10) The fake and inferior rectangular tubes are easy to be scratched, because the manufacturers of fake and inferior rectangular tubes have simple equipment, which are prone to burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.

11) The inner diameter of the fake and inferior rectangular tube fluctuates greatly because:

a. The steel temperature is unstable and there are yin and yang sides;

b. The composition of the steel is not uniform;

c. Due to the simple equipment, low strength of the foundation, and large bouncing of the rolling mill, such steel bars are easily broken due to uneven stress.

12) The trademark and printing of high-quality tubes are relatively standardized.

13) The longitudinal bars of shoddy steel rebar are often wavy.

14) The spacing of rectangular tubes with a diameter of more than 16 is more than IM.