1. The trademarks and printing of high-quality
spiral steel pipes are relatively standard.
2. The composition of high-quality steel is uniform, the tonnage of the cold shear machine is high, and the end face of the cutting head is smooth and regular. However, due to poor raw materials, the end face of the cutting head of defective steel often has the appearance of losing meat, that is, it is uneven and has no metallic luster. And because the products of defective wood manufacturers have fewer heads, big ears will appear at the head and tail.
3. Defective spiral steel pipes often have pitted surfaces on their surfaces. Pockmarks are irregular and uneven defects on the surface of the steel caused by serious wear and tear of the rolling grooves. Because inferior spiral steel pipe manufacturers seek profits, groove rolling often appears to be the most expensive.
4. The surface of defective spiral steel pipes is prone to scarring.
5. The surface of defective wood is prone to cracks because its raw material is adobe, which has many pores. The adobe is subjected to thermal stress during the cooling process, causing cracks, and cracks appear after rolling.
6. Defective thick-walled spiral steel pipes are easy to scratch. The reason is that the defective spiral steel pipe manufacturers have poor equipment and are prone to burrs and scratches on the surface of the steel. Deep scratches to the strength of falling steel.
7. Defective spiral steel pipes have no metallic luster and are light red or similar in color to pig iron.
8. For spiral steel pipes with large threads with a diameter of 16 or more, the distance between the two trademarks is above IM.
9. The longitudinal bars of defective steel rebar are often wavy.
10. The defective spiral steel pipe manufacturers are relatively lax in packaging because they do not have trucks. oval side
11. The transverse ribs of inferior spiral steel pipes are thin and low and often appear to be underfilled. The reason is that to achieve a large negative tolerance, the manufacturer’s reduction in the first few passes of the product is too large, the iron shape is too small, and the hole pattern is not filled.
12. The cross-section of inferior spiral steel pipes is oval. The reason is that to save materials, the reduction amount of the first two passes of the finished roller is too large. The strength of this kind of rebar is greatly reduced, and it does not meet the appearance standards of rebar. standards.
13. Defective spiral steel pipes contain a lot of impurities, the density of the steel is small, and the size tolerance is serious, so it can be weighed and checked without a vernier caliper.
14. The inner diameter of inferior spiral steel pipes fluctuates greatly.
15. Defective spiral steel pipes are prone to folding. Folds are various fold lines formed on the surface of spiral steel pipes. This defect often runs throughout the longitudinal direction of the product. The reason for folding is that inferior manufacturers pursue high efficiency and the reduction is too large, causing ears. Folding occurs during the next rolling process. The folded product will crack after bending, and the strength of the steel is greatly reduced.
