1. False and inferior rectangular tubes are easy to fold. Folding is a variety of broken lines formed on the surface of rectangular tubes, and this defect often runs through the longitudinal direction of the entire product. The reason for folding is that the manufacturers of fake and inferior rectangular tubes pursue high efficiency, the reduction is too large, and ears are produced. The folding occurs during the next rolling. The folded products will crack after bending, and the strength of steel will be greatly reduced.
2. The appearance of fake and inferior rectangular pipes is often pitted. Pitted surface is a kind of irregular uneven defect on the surface of rectangular tube caused by serious wear of rolling groove. Due to the pursuit of profits by manufacturers of fake and inferior rectangular tubes, the grooving rolling often exceeds the standard.
3. The surface of fake and inferior rectangular tubes is easy to produce scabs. There are two reasons: (1) The fake and inferior rectangular tubes are made of uneven materials with many impurities. (2)。 The guide equipment of fake and inferior rectangular pipe manufacturers is simple and crude, and easy to stick steel.
4. The surface of fake and inferior steel is easy to crack, because its billet is adobe, and there are many pores in adobe. The adobe is cracked due to the effect of thermal stress in the cooling process, and cracks appear after rolling.
5. Fake and inferior rectangular tubes are easy to be scratched, because the manufacturer of fake and inferior rectangular tubes has simple 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 has two reasons. Its blank is adobe. The rolling temperature of fake and substandard materials is not standard, and their steel temperature is measured by visual inspection, so that the steel cannot be rolled according to the specified austenite area, and the performance of steel cannot meet the standard naturally.