1. Fake and inferior steel are easy to fold. Folding is a variety of folding lines formed on the surface of steel, and this defect usually runs through the entire longitudinal direction of the product. The reason for the folding is that the fake manufacturer pursues high efficiency and the reduction is too large, resulting in ear plugs. The folding will occur in the next rolling process. The product after bending will break, and the strength of the steel will be greatly reduced.
2. The appearance of fake and inferior steel often has pitting. The pitting surface is an irregular steel surface caused by severe wear of the rolling groove. As fake and inferior steel manufacturers pursue profits, the slotting speed often exceeds the standard.
3. The surface of inferior steel is easy to leave scars.
There are two reasons: ①The materials of fake and inferior steel are uneven and have many impurities. ②The guide and protective equipment of the manufacturers of fake and inferior materials are simple and easy to stick to the steel. These impurities can easily cause scars after biting the roller.
4. The surface of fake and inferior materials is easy to break because its blank is adobe with many holes. The blank will be subjected to thermal stress during the cooling process, which will cause cracks, and cracks will appear after rolling.
5. The steel of counterfeit and inferior materials is easy to scratch because the equipment of counterfeit and inferior material manufacturers is simple, which is easy to produce burrs and scratch the surface of the steel. Deep scratches will reduce the strength of steel.
6. Counterfeit steel has no metallic luster and is light red or similar to pig iron. There are two reasons: ① Its blank is Adobe. ② The rolling temperature of counterfeit and inferior materials does not meet the standard, and its steel temperature is checked by the naked eye, so it cannot be rolled in the prescribed austenite area, and the performance of steel will naturally not meet the standard.
7. The ribs of fake steel are thin and low, and dissatisfaction often occurs. The reason is that to obtain a large negative tolerance, the reduction of the first few passes of the finished product is too large, the iron type is too small, and the hole type is not satisfied.
8. The cross-section of counterfeit steel is elliptical. The reason is that to save materials, the manufacturer reduces the first two passes of the finished roll. The strength of this kind of steel bar is greatly reduced and does not meet the standard of the steel bar shape.
9. High-quality steel has a uniform composition, high cold shear tonnage, and a flat end face of the cutting head. However, due to poor material quality, the end face of the cutting head often has the phenomenon of meat loss, that is, uneven and without metallic luster. Moreover, because the products of counterfeit and inferior material manufacturers are less cut, big ears will appear at the end.
10. Fake and inferior steel contains a lot of impurities, the steel density is small, and the size is seriously beyond the tolerance range, so it can be weighed and checked without a vernier caliper. For example, for steel bar 20, the national standard stipulates that the maximum negative tolerance is 5%. When the length is 9M, its single theoretical weight is 120 kg. Its minimum weight should be: 120X (l-5%) = 114 kg, and the actual weight of the single piece weighed is less than 114 kg, which is counterfeit and inferior steel because its negative tolerance exceeds 5%. Generally speaking, the cumulative error and probability theory problems are mainly considered, and the whole phase weighting effect will be better.
11. The inner diameter of fake and inferior steel fluctuates greatly because of; ① The steel temperature is unstable and there are yin and yang sides. ② The steel composition is uneven. ③ Due to the simple equipment, low foundation strength, and large bounce of the rolling mill. There will be a large change in the inner diameter within the same week, and such steel bars are prone to fracture due to uneven force.
12. The trademarks and printing of high-quality materials are relatively standardized.
13. For large threads with a steel diameter of 16 or more, the distance between the two trademarks is greater than IM.
14. The longitudinal steel bars of inferior steel bars are usually wavy.
15. Inferior steel manufacturers pack loosely because they don’t drive. The side is oval.
Post time: Oct-14-2024