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How to identify the advantages and disadvantages of seamless steel pipes

浏览: Release time: 2019-11-04 10:21 Times

1. Fake thick-walled seamless steel pipes are prone to folding. Folding is a variety of fold lines formed on the surface of thick-walled seamless steel tubes, and this defect often runs through the entire product in the longitudinal direction. The reason for the folding is that the inferior manufacturers are pursuing high efficiency, the reduction is too large, and ears are generated. When the next rolling is performed, the folding occurs. The folded product will crack after bending, and the strength of the thick-walled seamless steel pipe is greatly reduced. .
2. The appearance of shoddy thick-walled seamless steel pipes is often pitted. The matte surface is caused by the irregular unevenness of the surface of the thick-walled seamless steel pipe due to the severe groove wear. Because manufacturers of fake and inferior thick-walled seamless steel pipes are pursuing profits, it often appears that the rolling of grooves exceeds the standard.
3. The surface of fake and thick thick seamless steel pipes is prone to scarring. There are two reasons for this: Inferior thick-walled seamless steel pipes are uneven in material and have many impurities. 2. The guide equipment of the fake and inferior materials manufacturers is simple and easy to stick to steel. These impurities are easy to scar after they bite the roller.
4. The surface of the fake and inferior materials is prone to cracks, because the billet is adobe, and the adobe has many pores. During the cooling process, the adobe is cracked due to thermal stress and cracks are formed after rolling.
5. Fake and thick-walled seamless steel pipes are easy to scratch. The reason is that the manufacturers of fake and inferior materials are rudimentary and prone to burrs and scratch the surface of thick-walled seamless steel pipes. Deep scratches reduce the strength of thick-walled seamless steel pipes.
6. The inferior thick-walled seamless steel pipe has no metallic luster and is pale red or a color similar to pig iron. There are two reasons for this. Its billet is adobe. 2. The rolling temperature of fake and inferior materials is not standard, and their steel temperature is measured through visual inspection. In this way, rolling cannot be performed according to the specified austenite region, and the performance of thick-walled seamless steel tubes cannot naturally meet the standards.
7. The cross bars of the inferior thick-walled seamless steel pipes are thin and low, and the phenomenon of full dissatisfaction often occurs. The reason is that in order to achieve large negative tolerances, 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 full.
8. The cross section of the inferior thick-walled seamless steel pipe is oval. The reason is that in order to save materials, the reduction of 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 rebar external dimensions. Standard.
9. The composition of high-quality thick-walled seamless steel pipes 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 quality of the inferior materials, the end face of the cutting head often has meat dropping, that is, unevenness and no metallic luster . And because fake and inferior materials manufacturers have fewer cuts, big ears will appear at the head and tail.
10. The material of fake and thick-walled seamless steel pipe contains a lot of impurities, the density of steel is small, and the size is very bad, so it can be weighed and checked without a vernier caliper. For example, for the rebar 20, the national standard stipulates that the maximum negative tolerance is 5%. When the fixed length is 9M, its single theoretical weight is 120 kg. Its minimum weight should be: 120 X (l-5%) = 114 kg. If the actual weight of the single root weighed is less than 114 kg, it is a fake thick-walled seamless steel pipe because the negative tolerance exceeds 5%. Generally speaking, the effect of phase weighing is better, and the problems of cumulative error and probability theory are mainly considered.
11. The internal diameter of the fake and thick thick seamless steel pipe fluctuates greatly due to the following reasons: l, the temperature of the steel is unstable and has a positive and negative surface. 2. The composition of steel is not uniform. 3. Due to the simple equipment and low foundation strength, the bouncing of the rolling mill is large. There will be a large change in the inner diameter within the same week, and this kind of reinforcing steel is uneven and prone to fracture.
12. The trademarks and printing of high-quality materials are relatively standardized.
13. For three thick-walled seamless steel pipes with a diameter of 16 or more, the spacing between the two trademarks is above IM.
14. The longitudinal tendons of counterfeit thick-walled seamless steel pipe rebar are often wavy.
15. Manufacturers of counterfeit thick-walled seamless steel pipes are loosely packed because they do not have traffic. The sides are oval.

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