1. 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.
2. 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.
3. The surface of the fake and inferior rectangular tube is prone to scarring. There are two reasons: (1). The material of the fake and inferior rectangular tube is uneven and there are many impurities. (2). Fake and shoddy manufacturers have poor guide equipment and are easy to stick to steel. These impurities
4. The surface of the fake and inferior material is prone to cracks, because its blank is adobe, and the adobe has many pores, and the adobe is subjected to thermal stress during the cooling process, resulting in cracks. After rolling, there are cracks.
5. The fake and inferior rectangular tubes are easy to be scratched, because the manufacturers of fake and inferior rectangular tubes have simple equipment, which is easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.
6. 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 the rolling cannot be carried out according to the specified austenite area, and the performance of the steel will naturally fail to meet the standard.
7. The transverse ribs of the fake and inferior rectangular tubes are thin and low, and there is often a phenomenon of dissatisfaction. The reason is that the manufacturer has a large negative tolerance, and the pressure of the first few lines of the finished product is
8. 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.
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. However, due to the poor material of the fake and inferior material, the end face of the cutting head often has the phenomenon of falling meat, 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.
