Identification of counterfeit and thick-walled seamless steel tubes

- Apr 09, 2018-

1.The pseudo-thick-walled seamless steel pipe is prone to collapse. Folding is the formation of a variety of fold lines on the surface of thick-walled seamless steel tubes. Such defects often run through the entire product. The reason for the folding is due to the high efficiency of the shoddy manufacturers, the large amount of reduction, the generation of ears, and the folding of the folded products. The folded products will crack after bending, and the strength of the thick-walled seamless steel tubes will decrease greatly. DIN2502 Flange


2. Counterfeit thick-walled seamless steel pipe often has pockmarked appearance. Mamian is a defect caused by the irregular wear and tear of the thick-walled seamless steel pipe due to the wear of the groove. Due to fake and thick thick-walled seamless steel pipe manufacturers to seek profits, rolling slot rolling is often the most excessive.


3. Pseudo-inferior thick-walled seamless steel pipe surface is prone to scarring. There are two reasons for this: 1. Inhomogeneous thick-walled seamless steel tubes are not uniform in material and contain many impurities. 2. The inferior guide manufacturers' equipment is simple and easy to stick to steel, and these impurities are easy to produce scars after being bitten by rollers. reducer tee


4. The surface of the inferior material is prone to cracks because its blank is adobe and the porosity of the blank is large. The adobe is subjected to thermal stress during the cooling process and cracks are generated. After the rolling, cracks occur.


5. Counterfeit and thick-walled seamless steel pipes are easy to be scratched. The reason is that the counterfeit and inferior materials manufacturers are poorly equipped, prone to burrs, and scratch the surface of thick-walled seamless steel pipes. Deep scratches reduce the strength of thick-walled seamless steel tubes.butt welding tee


6. Pseudo-inferior thick-walled seamless steel tubes have no metallic luster and are pale red or similar to that of cast iron. There are two reasons for this. The blanks are adobe. 2. The temperature of the shoddy material rolling is not standard. Their steel temperature is measured visually, so that the rolling cannot be carried out according to the prescribed austenitic region. The performance of thick-walled seamless steel tubes naturally cannot be achieved.


7. The horizontal and vertical thin-walled steel pipes of the fake and thick seamless steel tubes are thin and low, and the phenomenon of insufficient filling often occurs. The reason is that the manufacturers have to achieve large negative tolerances, the amount of reduction in the first few passes of the finished products is too large, the iron type is too small, and the hole type is small. dissatisfied.


8. The cross-section of fake-thick thick-walled seamless steel tubes is elliptical. The reason is that in order to save materials, the amount of reduction before the finished roll is too large. The strength of this rebar steel is greatly reduced, and it is not in line with rebar. The dimensions of the standard.butt welding cap


9. High-quality thick-walled seamless steel pipe has uniform composition, high tonnage of cold-shearing machine, and smooth and neat end face, and the inferiority of the material due to poor quality is often caused by the phenomenon of falling meat on the end face of the cutting head. Metallic luster. Moreover, due to the lack of cut-to-size products from manufacturers of inferior and inferior products, big ears will appear at the head and tail.


10. Pseudo-inferior thick-walled seamless steel pipe material contains many impurities, the density of the steel is small, and the size of the ultra-thin ultra-diffraction serious, so without the vernier caliper, it can be weighed and checked. For example, for rebar 20, the national standard specifies a maximum negative tolerance of 5%. When the length is 9M, its single theoretical weight is 120 kg. Its minimum weight should be: 120 X (l-5%) = 114 kg. The actual weighing of a single root weighing less than 114 kilograms is a pseudo-inferior thick-walled seamless steel pipe because its negative tolerance exceeds 5%. In general, the effect of phasing is better, mainly considering cumulative error and probability theory.