1. Shoddy
brass tubes are prone to folding. Folding is a variety of fold lines formed on the surface of the brass tube, and this defect often runs through the longitudinal direction of the entire product. The reason for the folding is that the fake and inferior manufacturers pursue high efficiency, the reduction is too large, the ear occurs, and the folding occurs in the next rolling process. The folded product will crack after bending, and the strength of the thick-walled seamless pipe will be greatly reduced.
2. The surface of fake and inferior brass tubes often has pockmarks. Pockmarked surface is due to the serious wear and tear of the rolling groove, which leads to the irregular and uneven surface of the brass tube. Because manufacturers of fake and inferior brass tubes want to pursue profits, groove rolling often exceeds the standard.
3. Shoddy brass tubes are prone to scarring on the surface. There are two factors:
(1) The raw materials of fake and inferior brass tubes are uneven and have many impurities.
(2) The guides and guards of fake and inferior material manufacturers are poorly equipped and easy to stick to steel. These impurities are prone to scarring after biting the roll.
4. Cracks are easy to occur on the surface of fake and inferior materials. 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, cracks occur, and there are cracks after rolling.
5. Fake and inferior brass tubes are easy to scratch. The reason is that the manufacturers of fake and inferior materials have poor equipment, which is prone to burrs and scratches on the surface of the brass tube. Deep scratches reduce the strength of the brass tube.
6. Shoddy brass tubes have no metallic luster and are light red or similar in color to pig iron. There are two factors:
(1) Its blank is adobe.
(2) The rolling temperature of fake and inferior materials is not standard. Their steel temperature is measured visually, so they cannot be rolled according to the designated austenite area, and the performance of the brass tube is naturally unqualified.
7. The horizontal ribs of fake and inferior thick-walled seamless pipes are thin and low, and there is often a phenomenon of dissatisfaction. dissatisfied.
8. The cross-section of fake and inferior brass tubes is oval. The reason is that in order to save materials, the reduction in the first two passes of the finished roll is too large. The strength of this rebar is greatly reduced, and it does not meet the standard of rebar shape. .
9. The composition of the high-quality brass tube is uniform, the tonnage of the cold shear is high, and the end face of the cutting head is smooth and clean. However, due to the poor raw materials of fake and inferior materials, the end face of the cutting head often has meat loss, that is, it is uneven and has no metallic luster. And because the fake and inferior material manufacturers have fewer heads, big ears will appear on the head and tail.
10. The raw materials of fake and inferior thick-walled seamless pipes contain many impurities, the density of the steel is relatively small, and the specification is seriously out of tolerance, so it can be weighed and checked without a vernier caliper. For example, for rebar 20, the standard stipulates that the maximum tolerance is 5%, and its single theoretical weight is 120 kg when the length is 9M, and its small weight should be: 120X (l-5%) = 114 kg , The actual weight of a single piece weighed out is less than 114 kg, it is a fake and inferior brass tube, because it has a negative tolerance of more than 5%. Generally speaking, the whole equivalence effect will be very good, mainly considering the problem of cumulative error and probability theory.
11. The internal diameter standard of fake and inferior thick-walled seamless square tubes fluctuates greatly, and there are three factors:
(1) The steel temperature is unstable and has a yin and yang side.
(2) The composition of the steel is uneven.
(3) Due to poor equipment and low foundation strength, the rolling mill has a large bounce. There will be a large change in the inner diameter within a consistent week, and such steel bars are prone to cracking due to uneven stress.
