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Identification of steel pipes
1. Fake and inferior steel pipes are prone to folding.
Folding is a variety of fold lines formed on the surface of a steel pipe that tends to extend throughout the longitudinal direction of the product. The reason for the folding is that the inferior manufacturer pursues high efficiency, the amount of pressing is too large, and the ear is produced, and the next rolling causes folding, and the folded product is cracked after bending, and the strength of the steel is greatly reduced.
2. The appearance of counterfeit steel pipes often has pockmarks.
The pockmark is a defect caused by the irregularity of the surface of the steel due to the serious wear of the groove. Due to the pursuit of profit by shoddy steel pipe manufacturers, the most frequent rolling mill rolling is exceeded.
3. The surface of the counterfeit steel pipe is prone to scarring.
There are two reasons for this: (1). The material of the fake steel tube is uneven and has many impurities. (2). The fake inferior material manufacturer's guiding equipment is simple and easy to stick steel. These impurities are easy to produce crusting after biting the roller.
4. The surface of the fake inferior material is prone to cracks because the billet is adobe, the adobe has many pores, and the adobe is cooled.
During the process, cracks are generated due to thermal stress, and cracks occur after rolling.
5. Fake and inferior steel pipes are easy to scratch, because the equipment of the fake and inferior steel pipe manufacturers is simple, easy to produce burrs and scratch the surface of the steel. Deep scratches reduce the strength of the steel.
6. The fake steel tube has no metallic luster and is light red or similar to pig iron. The reason is two points. The billet is adobe. 2, the temperature of the fake inferior material rolling is not standard, their steel temperature is measured by visual inspection, so that it can not be rolled according to the specified austenite area, the performance of the steel naturally cannot meet the standard.
7. The cross-fabricity of the inferior steel pipe is thin and low, and the phenomenon of filling and dissatisfaction often occurs. The reason is that the manufacturer has to achieve a large negative tolerance, the amount of pressing of the first few passes of the finished product is too large, the iron type is small, and the hole type is not full.
8. The cross-section of the counterfeit steel pipe is elliptical. The reason is that the manufacturer has to reduce the amount of the two rolls in front of the finished roll in order to save material. The strength of the rebar is greatly reduced, and it does not meet the standard of the rebar dimensions.
9. The composition of the 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 quality of the fake inferior material, the end face of the cutting head often has a phenomenon of falling meat, that is, unevenness and no metallic luster. And because the fake inferior products manufacturers have fewer heads, big ears will appear at the head and tail.
10. The fake steel pipe material contains many impurities, the density of the steel is small, and the size is too bad, so in the absence of the vernier caliper, it can be weighed and checked. For example, for rebar 20, the national standard specifies a large negative tolerance of 5%. At a fixed length of 9M, its single theoretical weight is 120 kg. Its small weight should be: 120X (l-5%) = 114 kg. The actual weight of a single root is less than 114 kg, which is a fake steel because its negative tolerance exceeds 5%. In general, the effect of the phasing weighing will be better, mainly considering the problem of cumulative error and probability theory.
11. The inner diameter of the inferior steel pipe fluctuates greatly because of the reason; l, the steel temperature is unstable and there is a yin and yang surface. 2. The composition of steel is not uniform. 3. Due to the simplistic equipment, the foundation strength is low, and the rolling mill has a large bounce. There will be a large change in the same week, and such a steel bar is unevenly stressed and easily broken.
12. The trademark and printing of the tube are relatively standardized.
13. The three-diameter steel pipe has a diameter of 16 or more, and the distance between the two trademarks is above IM.
14. The longitudinal reinforcement of the counterfeit steel rebar is often wavy.
15. Because the fake steel pipe manufacturers do not have driving, the packaging is relatively loose. The sides are oval.