1. The trademark and printing of the high-quality tube are comparable to the standard.
2. The composition of high-quality steel is uniform, the tonnage of the cold shearing machine is high, and the end face of the cutting head is smooth and regular, while the inferior material often has the appearance of falling flesh on the end face of the cutting head due to poor raw materials, that is, unevenness and no metallic luster. And because the products of the inferior wood manufacturers have fewer cutting heads, the heads and tails will have big ears.
3. The surface of the inferior
spiral steel pipe often has a pockmarked surface. The pitted surface is due to the serious wear of the rolling groove, which causes the irregularity of the surface of the steel. Because the inferior
spiral steel pipe manufacturers want to seek profit, the most overrun of groove rolling often occurs.
4. The surface of the defective
spiral steel pipe is prone to scarring.
5. The surface of the inferior material is prone to cracks, because its blank is adobe, and the adobe has many pores. During the cooling process of the adobe, cracks occur due to thermal stress, and cracks occur after rolling.
6. The inferior thick-walled
spiral steel pipe is easily scratched because the inferior
spiral steel pipe manufacturer has simple equipment, which is prone to burrs and scratches the surface of the steel. The strength of deep scratching of falling steel.
7. The inferior
spiral steel pipe has no metallic luster and is light red or similar to pig iron.
8. For the large thread of the three-
spiral steel pipe with a diameter of 16 or more, the distance between the two trademarks is more than IM.
9. The longitudinal bars of inferior steel rebars are often wavy.
10. Because the manufacturers of inferior
spiral steel pipes do not have traffic, the packaging is relatively lax. oval side
11. The transverse bars of the inferior
spiral steel pipe are thin and low, and often appear unsatisfactory. The reason is that to achieve a large negative service, the reduction amount of the first few passes of the product is too large, the iron shape is too small, and the hole shape is not full enough.
12. The cross-section of the inferior
spiral steel pipe is oval. The reason is that to save materials, the reduction amount of the first two passes of the product roll is too large. standard.
13. The material of the inferior
spiral steel pipe contains a lot of impurities, the density of the steel is too small, and the scale is out of tolerance, so it can be weighed and checked without a vernier caliper.
14. The inner diameter of the inferior
spiral steel pipe fluctuates greatly.
15. The inferior
spiral steel pipe is easy to fold. Folding is a variety of fold lines formed by the surface of the
spiral steel pipe, and this defect often runs through the longitudinal direction of the entire product. The reason for the folding is that the inferior manufacturers seek high efficiency, the reduction amount is too large, the ear is formed, and the folding occurs during the next rolling. The folded product will crack after being bent, and the strength of the steel will drop greatly.
