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 due to the pursuit rate of the inferior manufacturers, the amount of pressing is too large, the ear is generated, and the folding occurs during the next rolling, and the folded product is cracked after being bent, and the strength of the steel is greatly reduced.

2. The appearance of fake 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 the inferior steel pipe manufacturers, the rolling mills often exceed the standard.

3, the surface of the fake steel pipe is prone to scarring.

There are two reasons for this:

1) The material of the fake steel pipe is uneven and has many impurities.

2) The guide equipment of the fake inferior material manufacturer 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, due to the action of thermal stress, cracks are generated and cracks occur after rolling.

5, the fake steel pipe is easy to scratch, the reason is that the equipment of the fake and inferior steel pipe manufacturers is simple, easy to produce burrs, scratching the steel surface. Deep scratches reduce the strength of the steel.

6, the fake steel pipe has no metallic luster, is light red or similar to the color of pig iron, for two reasons, its 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 region, and the performance of the steel is naturally unable to reach 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 reached a large negative tolerance, the amount of reduction 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 inferior 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 size. .

9. The composition of the steel is uniform, the tonnage of the cold shearing machine is high, the end face of the cutting head is smooth and tidy, and the fake inferior material is often poor in material, and 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 more impurities, the density of steel is too small, and the size is too bad, so in the absence of vernier calipers, it can be weighed and checked. For example, for rebar 20, the standard specifies a negative tolerance of 5%. At a fixed length of 9 M, its single theoretical weight is 120 kg. Its weight should be: 120X (l-5%) = 114 kg. The actual weight of the root is less than 114 kg, which is a fake steel because its negative tolerance exceeds 5%. In general, the phasing weighing effect will be good, mainly considering the problem of cumulative error and probability theory.

11. The inner diameter of the inferior steel pipe fluctuates greatly because of:

l) The temperature of the steel is unstable and there are yin and yang faces.

2) The composition of the steel is not uniform.

3) Due to the simplification of the 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. Three large steel pipes with a diameter of 16 or more, the spacing between the two trademarks is above IM.

14. The longitudinal reinforcement of the counterfeit steel rebar is often wavy.

15, the fake steel pipe manufacturers because there is no driving, so the packaging is relatively loose. The sides are oval.