How to Identify Seamless Steel Tube
1. The thick seamless steel tube with poor quality is easy to fold. This defect is often found in the longitudinal direction of the whole product. Causes of fold is due to the pursuit of the false and inferior, high efficiency, large reduction, handle, when the next rolling produce folding, folding products will be cracking after bending, the strength of the large thick wall seamless steel tube.
2. The appearance of pseudo – inferior thick – walled seamless steel tube often has the appearance of hemp. The surface of the flax is the irregularity of the surface of the thick – walled seamless steel tube due to serious groove wear. Because the manufacturer of fake and inferior thick seamless steel tube wants to pursue profit, often appear groove rolling the most superstandard.
3. Pseudo – inferior thick – wall seamless steel tube surface is prone to scarring.
There are two reasons:
1. The fake thick seamless steel pipe is not uniform in material and has many impurities.
2. The guide equipment of the manufacturer of fake and inferior materials is simple and easy to stick steel.
4. And inferior material surface cracks easily, because its billet is adobe, adobe air, adobe in the process of cooling due to the effect of thermal stress, cracks, after rolling there is crack.
5. Fake and inferior thick seamless steel tube is easy to scratch, because the manufacturer of fake and inferior materials equipment is simple, easy to produce burrs, scratch thick seamless steel tube surface. Deep scratches reduce the strength of thick – walled seamless steel tubes.
6. The fake thick wall seamless steel tube has no metallic luster and is a reddish color or similar to pig iron, for two reasons. 2, and inferior material rolling temperature is not standard, their steel temperature is through visual inspection, so can’t austenitic area of the rolling by the regulation, the performance of the thick wall seamless steel tube nature is not up to standard.
7. And inferior transverse reinforcement of thin and thick wall seamless steel tube is low, often appears phenomenon of discontent, because manufacturers to achieve big minus tolerance, finished product quantity of the previous way slants big, small iron type, groove filling.
8. And inferior thick-walled seamless steel tube cross-section oval, because the factory in order to save material, the quantity of the finished product roll before 2 slants big, the strength of rebar is greatly decreased, but also do not conform to the standard of rebar shape size.
9. Quality ingredients evenly thick wall seamless steel tube, cold shearing machine high tonnage, cutting head end face smooth and neat, and shoddy material because the material is poor, cutting head end face often have meat, or uneven, and no metallic luster. And because the manufacturer of fake and inferior materials products cut the head less, the head and tail will appear big ears.
10. The fake thick wall seamless steel pipe material contains many impurities, the density of steel is small, and the size difference is serious, so it can be weighed and checked without vernier caliper. For rebar 20, for example, maximum minus tolerance specified in the national standard of 5%, scale of 9 m in the theory of single weight is 120 kg, it should be the smallest weight: 120 X (l – 5%) = 114 kg and 114 kg weigh out the weight of the single than small, is false and inferior thick-walled seamless steel pipe, because it is minus tolerance more than 5%. Generally speaking, the effect of integral proportionality is better, mainly considering the cumulative error and probability theory.
11. The size of the inside diameter of the pseudo – inferior thick – walled seamless steel tube fluctuates greatly because of the following reasons: L. The temperature of steel is unstable with a Yin and Yang surface. 2. The composition of steel is not even. 3. Because of simple equipment and low foundation strength, the rolling mill has a large bounce. There will be a large change in the inner diameter within the same week, so the reinforcement forces are not uniform and easy to break.
12. The trademark of high quality material and printing are more standard.
13. Large thread with a diameter of more than 16 in the seamless steel pipe with three thick walls, and the spacing between the two trademarks is above IM.
14. The longitudinal bars of pseudo – inferior thick – walled seamless steel tubes are often wavy.
15. Fake thick wall seamless steel pipe manufacturers because there is no driving, so relatively loose packaging. The side is oval.