1. Shoddy steel prone to folding.
  Folding Rectangular steel pipe, steel pipe surface to form a variety of polylines, such defects are often longitudinally throughout the product. The reason is due to shoddy manufacturers of folding the pursuit of high efficiency, reduction is too large, resulting in the ears, to produce a rolling fold down when the product will crack when folded bend strength of steel big drop.
  2. Shoddy steel exterior often pitted surface phenomenon.
  Pock is due to badly worn groove steel surface irregularities caused by uneven defects. Because of shoddy steel manufacturers have to pursue profits, rolling groove most often exceeded.
  3. Shoddy steel surface is easy to produce scarring.
  There are two reasons: (1). Shoddy steel material uneven impurities. (2). Shoddy material manufacturers guide and guard the poorly equipped, easy to stick steel, easy to produce scarring after the roll bite these impurities.
  4. Too easy to crack the surface of shoddy material, because it is blank adobe, adobe pores more adobe in cooling
  5. Shoddy steel easily scratched because of shoddy steel equipment is very easy to produce burrs, scratches steel surface. Deep scratches reduce the strength of steel.
  6. Non-metallic pipe inferior, pale red color of iron or the like, there are two two reasons, it is blank adobe. 2, shoddy-rolling temperature is not standard, they are visually steel temperature, so that the region can not be prescribed by the austenitic rolling, the natural properties of the steel can not be reached.
  7. Shoddy steel cross ribs thin and low, often sufficient dissatisfaction phenomenon, because manufacturers to achieve large negative tolerance, finished the first few tracks reduction is too large, iron-type small, hole filling dissatisfaction.
  8. Shoddy steel oval in cross section, because the manufacturers in order to save material, the first two tracks reduction of finished roll is too large, the strength of this steel is greatly decreased, and does not meet the standard dimensions of rebar.
  9. Uniform quality steel components, high tonnage cold shear, cut the head face smooth and neat, because the material is poor and shoddy materials, there are often cut off the meat head end face of the phenomenon, namely uneven, and no metallic luster. And because the wood product manufacturers cut shoddy little head, head and tail will be a big ears.
  10. Shoddy steel material containing impurities, the density of steel is small, and the size tolerance serious, so in case of the absence of a vernier caliper, check that it can be weighed. For example, steel 20, the national standard specifies the maximum negative tolerance is 5% of its length when 9M single theoretical weight of 120 kg, its weight should be minimal: 120X (l-5%) = 114 kg weigh out the actual weight of 114 kg single smaller than it is shoddy steel, because it is a negative tolerance of 5%. Generally the whole proportionate amount would be better, mainly taking into account the cumulative error and probability theory this problem.
  11. Shoddy steel pipe inner diameter fluctuations due; l, steel surface temperature instability of yin and yang. 2, the composition of the steel uniform. 3, due to poor equipment, low-intensity ground, bouncing big mill. There will be a large change in the same week, so easy to produce steel discontinuity fracture.
  12. Trademarks and print quality pipes are relatively standardized.
  13. Three pipe diameter of more than 16 large thread pitch between the two trademarks are IM or more.
  14. Inferior longitudinal reinforcement steel rebar often wavy.
  15. Shoddy steel pipe manufacturers because there is no traffic, so the package is relatively loose. Side of the oval.