New knowledge: 15 methods of identification of inferior steel pipes
October 10, 2018
1. Counterfeit pipes are prone to collapse.
Folding is a variety of fold lines formed on the surface of the steel pipe, and this defect often runs 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 folding products will crack after bending and the strength of the steel will drop.
2. Counterfeit steel pipe surface often has pockmarked phenomenon.
The pockmark is due to the irregular wear and tear of the surface of the steel due to the wear of the groove. Because shoddy steel pipe manufacturers are pursuing profits, rolling slot rolling is often the most excessive.
3. Scrap steel pipe surface is prone to scarring.
There are two reasons for this: (1). The shoddy steel pipe has uneven material and 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.
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. The shoddy steel pipe is easy to be scratched because the equipment of the shoddy steel pipe manufacturer is simple and easy to generate burrs and scratch the steel surface. Deep scratches reduce the strength of the steel.
6. The shoddy steel tube has no metallic luster and is pale red or similar to the color of pig iron. There are two reasons for this. The blank is 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 the steel material naturally cannot be achieved.
7. The cross-bar of the shoddy steel pipe is thin and low, and the phenomenon of unsatisfactory filling often occurs. The reason is that the manufacturer has to achieve a large negative tolerance, the amount of reduction in 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 shoddy steel pipe is elliptical in cross-section because the manufacturer has to reduce the amount of material in front of the roll in order to save material. The strength of the rebar is greatly reduced, and it does not meet the standard for rebar size.
9. The composition of high-quality steel is even, the tonnage of the cold shears is high, and the end surface of the cutting head is smooth and neat, and the inferiority of the material due to poor quality is often due to the phenomenon of falling meat on the end surface of the cutting head, ie unevenness and no 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. The inferior steel pipe material contains many impurities, the density of the steel is small, and the size of the steel pipe is so bad that it can be weighed and checked without a vernier caliper. 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 weight of a single root weighed is less than 114 kilograms, which is a counterfeit steel because it has a negative tolerance of more than 5%. In general, the phasing effect will be better, mainly considering cumulative error and probability theory.
11. The size of the internal diameter of the shoddy steel pipe fluctuates greatly. The reason is that: l. The temperature of the steel is unstable and there is a yin-yang surface. 2, the composition of steel is not uniform. 3, due to the simple equipment, low strength of the foundation, the mill bouncing. There will be a large change in the same week, so that the steel reinforcement is not easy to produce fracture.
12. The quality of the logo and the printing of the tube are more standardized.
13. In the case of large threads with a diameter of 16 or more for steel pipes, the spacing between the two marks is above IM.
14. Spurs of steel rebar are often wavy.
15. The shoddy steel pipe manufacturers have looser packing because they have no driving. The side is oval.
