1. Shoddy square tube is prone to folding.

Folding is a variety of broken lines formed on the surface of the square tube, and this defect often runs through the longitudinal side of the entire product. The reason for folding is that the shoddy manufacturers pursue efficiency, the amount of pressure is too large, the ear is generated, the next rolling will fold, the folded product will crack after bending, and the strength of the steel will decrease.

2. The appearance of inferior square and rectangular pipes is often pockmarked.

Pitted surface is the irregular uneven defect of steel surface caused by severe groove wear. Due to the pursuit of profit by shoddy square pipe manufacturers, groove rolling often exceeds the standard.

3. The surface of shoddy square tube is prone to defects.

There are two reasons: (1). The material of shoddy square rectangular pipe is not uniform, and there are many impurities. (2). Shoddy material manufacturers guide equipment is simple, easy to stick steel, these impurities bite the roll is easy to produce defects.

4. The surface of shoddy materials is prone to cracks, the reason is that its billet is adobe, adobe porosity, adobe in the cooling too

Due to the action of thermal stress in the process, cracks occur, and cracks occur after rolling.

5. Shoddy thick wall pipe is easy to scratch, the reason is that shoddy square pipe manufacturers simple equipment, easy to produce burrs, scratch the steel surface. Scratches reduce the strength of steel.

6. The shoddy thick wall seamless square rectangular pipe has no metallic luster and is light red or similar to the color of pig iron, for two reasons. 2, the rolling temperature of shoddy materials is not standard, their steel temperature is visually measured, so that it can not be rolled according to the prescribed austenitic area, the performance of steel naturally can not meet the standard.

Seven. The transverse ribs of shoddy square rectangular pipes are thin and low, and the phenomenon of filling dissatisfaction often occurs, because the manufacturers in order to achieve large negative tolerances, the pressure of the first few passes of the finished products is too large, the iron shape is too small, and the pass shape is not full.

8. The cross section of the inferior square rectangular pipe is elliptical, because the manufacturer in order to save materials, the pressure of the first two rolls of the finished product is too large, the strength of this rebar is greatly reduced, and it does not meet the standard of the external size of the rebar.